Monday, September 24, 2012

The Patient Offense and the Spirit of the Rules

There's a lot of talk going on about rules changes and "stroller derby."  People are throwing out all sorts of radical ideas for new rules that would massively alter the game of flat track roller derby.  I usually ignore the gnashing of teeth.  I happen to think the rule set that WFTDA plays under is, for the most part, pretty damn good.  It's led to explosive growth for the sport, and I think drastically changing the rules by removing power jams or something extreme like that would be fixing what isn’t broken.  Still, the current WFTDA rule set is not perfect.  It’s definitely a work in progress.  People just need to realize that it needs to be honed, not rebuilt.

“Slow derby sucks!” is a familiar battle cry.  —But different people define different strategies as slow derby.  For me, slow derby used to always refer to the no/slow starts where the pack would just hang out behind the pivot line and the jammers would never be released.  That issue has largely been solved by counter-strategies like knee starting.  Other people hear “slow derby” and think of scrum starts.  I personally love scrum starts because I love seeing blockers engaging the jammer and working together.  Scrums are, by definition, engaging roller derby.  They just start off with slow-moving engagement.

When I think of slow derby today, I’m thinking about the patient offense/pace line strategy.  I hate, hate, hate this kind of roller derby.  I understand that it’s effective.  I understand that teams who want to win feel like they have to use this tactic in order to win important bouts.  They train really hard all year long to try and win, so why wouldn’t they do everything they can to win even if it means boos and alienating fans?  I get that.  It’s just a terrible abuse of the rules, and it's bad for the sport as a whole.

Let’s break this strategy down for a second and look at how the patient offense is taking advantage of a loophole.  The Springfield Isotopes jammer is sent to the penalty box giving the Shelbyville Maulers a power jam.  The Maulers choose to skate as slowly as possible on the outside line to try and convert the power jam into as many points as possible.  The rules do not say the pack has to maintain any specific speed.  All they say is that once the pack is in motion, the pace is set.  The blockers must stay within the bounds of the pack at whatever pace it is moving.

A pack that is moving at a quarter of a mile per hour is set at that pace and perfectly legal.  Once the pace of the pack is set at 0.25 mph, there is almost nothing that the Isotopes can do to speed it up.  The Maulers jammer engages the pack, and the Isotopes block her until there is a 10-foot gap between the teams, resulting in no pack and 5 points for the Maulers.  The rules require that both teams reform the pack, but once the teams are back within 10 feet of each other, the Maulers can just maintain a 9-foot gap (skating backwards if necessary), and thus force another quick no-pack and get another 5 points without doing much of anything.  Rinse and repeat.  Over and over.

The problem with this strategy is that it’s a tactic employed intentionally to destroy the pack.  Let me repeat that.  Pace line derby is intentional destruction of the pack.  I don't think anyone can argue this.  It may not be an active act of destroying the pack, but it is definitely a passive act of destroying the pack.

Let’s look at what the current WFTDA rules have to say about maintaining a pack:

4.1.2 - When two or more groups of Blockers equal in number are on the track; are more than 10 feet from one another; and no single group meets the pack definition, no pack can be defined. Skaters will be issued a penalty for intentionally creating a no pack situation i.e. destroying the pack (see Section 6.10.2). Both teams are responsible for maintaining a legally defined pack. A skater or group of skaters is always responsible for the consequences of their actions. If their actions create a no pack situation (except those covered in Section, they should be penalized as directed in Sections 6.10.9–6.10.24.

There’s the problem.  The rules state that both reams are responsible for maintaining a pack, but they only penalize “actions” that result in a no pack situation.  They do not say anything about inaction that results in a no pack situation.  Inaction which results in destruction of the pack may not be against the letter of the rules, but it is most definitely against the spirit of the rules.

So how is the patient offense any different than stopping altogether or just dropping to a knee?  It's not.  The patient offense is minimal movement which results in destruction of the pack.  It’s just that the current rules surrounding destroying the pack do not include instances where a team maintains an extremely slow pace to intentionally force a no pack situation.  There's a loophole allowing teams to intentionally destroy the pack without being penalized for it.

A lot of people want to overhaul the rules and define the pack as the group of blockers in the front... or include jammers as part of the pack... or something game-changing like that.  I would prefer WFTDA not use a sledgehammer and instead use a scalpel.  The simplest solution is to just close the loophole and define pace line derby as illegal destruction of the pack.  It’s the responsibility of both teams to maintain the pack, right?  Why not enforce that?  Referees already require skaters reform the pack when no pack exists.  Would it not also make sense to have referees require skaters to make an effort to maintain the pack?  I think that's perfectly reasonable, and it wouldn't really change the way roller derby is played.

Now let’s take a look at the current WFTDA rules regarding destruction of the pack: - Examples of illegally destroying the pack, or creating a “no pack” situation, may include but are not limited to: a skater, skaters or team running away, braking or coasting to drop back more than ten (10) feet behind the opposing team, taking a knee, intentionally falling, or intentionally skating out of bounds in such a manner that the legally defined pack is destroyed. - The rules do not define pack speed. Illegally destroying the pack penalties shall not be given for gradually deviating from the speed of the pack as established through game play, unless said deviation is sudden, rapid and marked, leaving the opposing team no opportunity to adjust and maintain a pack.

I highlighted the part about leaving no opportunity for the opposing team to maintain the pack here because that’s exactly what pace line derby does.  If the Isotopes blockers try to skate backwards to close the 9-foot gap and allow themselves a chance to engage the jammer while maintaining the pack, the Maulers will just skate backwards as well in order to maintain the 9-foot gap.  The idea is to basically keep the Isotopes on the edge of a cliff so that if they try to block the jammer, they end up destroying the pack and have to let her go anyway.  The pace line tactic is successful in that it leaves the opposing team no opportunity to both engage the jammer (play roller derby) and maintain the pack.  They have to choose one and not the other, which leaves the Isotopes blockers helpless and results in the Maulers racking up grand slams with little-to-no effort.

Section could simply be amended to include something like “inaction such as minimal movement which causes the natural continuation of play to result in a no pack situation” as an example of illegally destroying the pack.  It seems pretty simple to me.  If the rules included something like this, the Maulers would be compelled to engage the pack and try to trap an Isotopes blocker.

Regardless of how it’s worded, I really hope that this kind of rule change is enacted.  I know this isn’t a perfect solution, there may be no perfect solution, but I think it’s very important that WFTDA does something to incent teams to actively play roller derby.  Most of the time, I’m fine with letting counter-strategies develop to progress the sport.  I just happen to think that there are no real counter-strategies that can be developed to correct this quirk in the rules.  The patient offense is a great example of loophole exploitation, and in my opinion, the loophole just needs to be closed.

Tuesday, September 18, 2012

Jams Fielded Per Penalty Turn

Any educated fan can tell you that penalties are huge in roller derby.  If you read my stats study earlier this year on Queen of the Rink, then you have a pretty good idea of just how big they can be.  —And it seems like the effect that penalties have on the game is getting larger.  As teams begin to get closer in skill level and strategies continue to advance, losing skaters to the penalty box becomes more and more hindering.

Because of this, there is also an increased need for good penalty management tools.  I had experimented with some penalty frequency statistics like "minors per jam" [(majors × 4 + minors) / jams], but I was never satisfied with the usefulness of something like that.  I've seen other statistics like fractional penalty minutes that attempt to factor in the impact of minors to scale with majors, but again, those kinds of statistics are not very useful because of the difficulty in comprehending them.  In my opinion, a stat is only as useful as it is understandable.

One of the big problems is measuring penalty frequency by jams skated.  Jams skated is a good divisor in basic roller derby stats like points per jam or lead jam percentage.  It can give you useful averages for a lot of things, but not for penalty frequency.  The reason for this is because with penalty frequency statistics, serving a penalty turn can actually help a player's rating.

To illustrate what I'm talking about, let's look at 2 skaters who commit the same penalty.  Fannie Flash goes into the penalty box at the beginning of a jam and exits later in the same jam.  She skates in 1 jam and gets 1 major penalty.  That's a 1:1 ratio of penalties:jams skated.  In the next jam Rascal Rae goes to the penalty box for committing the same penalty, but the jam is called off shortly after she sits down.  Another jam passes, and then Rascal Rae exits the penalty box in a third jam.  In this case, the ratio of penalties:jams skated would be 1:3.  The problem is that Fannie and Rascal commit penalties at the same frequency.  Fannie had no control over the jam continuing and Rascal had no control over being in 2 more jams.  Using jams skated for penalty frequency statistics is unreliable.

The real question at hand is: "How often do skaters go to the penalty box when you send them into the game?"  The number of jams a skater is actually in is irrelevant.  If you subtract the number of times a skater begins the jam in the penalty box, from the number of jams she was in, you'll get the actual number times she was sent onto the track.  —Something I like to call Jams Fielded.  Hopefully, your lineup trackers are recording when skters enter and exit the penalty box.  If they do, this should be an easy stat to calculate.

Using Jams Fielded can really highlight how often skaters are actually sent onto the track and how often skaters just end up in the penalty box, stuck in the game for another jam.  Once you divide the jams fielded by the number of penalty turns a skater has incurred, you'll get the average number of times a skater is fielded before she goes to the penalty box.  This is the Jams Fielded Per Penalty Turn.  I love this stat because it's very simple to read.  A score of 6.25 means that every 6.25 times a skater has been sent into a jam, that skater has gone to the penalty box.  It's simple; the higher the score, the better.

So, how is this useful?  Well, obviously it's very useful to know how penalty prone every skater has been.  Keep in mind, though that you also have to take into account how active the skater is in the pack.  A skater who is an actively hitting blocker (doing the heavy lifting in the pack) is simply going to garner more penalties than a skater who usually just positionally blocks.  Still, it can be really helpful to know when you only have 2 blockers on the track because in that situation, you're need to get your team out of the penalty box carousel of doom.  Maybe in stead of putting in you 2 strongest blockers, you might want to put out a couple of clean blockers for a jam to try and get back to a 3-pack or a 4-pack for the following jam.  Sure they might not be as strong as other blockers, but sometimes losing a jam or two can be worth it if you are stronger in the pack for several jams afterwards.

Also, I highly recommend splitting this stat between jammer and blocker statistics (keep in mind that any poodling jammer is going to have a bad blocker score).  Obviously, it's far more important to have a clean jammer than a clean blocker.  One or two power jams is often the difference in winning or losing a bout.  If you can put together a clean jamming rotation, it can be a huge advantage.

In the end, this is all about managing penalties.  Your average 60-minute bout is going to be approximately 40-42 jams.  You can use Jams Fielded Per Penalty Turn to get an idea of how many penalties to expect from blockers team based on your lines.  You can use it to help predict the number of power jams you are likely to surrender based on your jamming rotation.  Sometimes just knowing what to expect ahead of time can help a team keep their heads and avoid compoinding penalties.  There are a lot of ways you can apply Jams Fielded Per Penalty Turn to help manage the game and give your team the best chance at winning.

Friday, February 24, 2012

In Defense of Power Jams

One of the most compelling parts of being involved in modern roller derby for me is the fact that the sport is still in its infancy. The future is unknown and full of possibilities. I get to experiment with things like roller derby stats because no one has ever done it before. The book has yet to be written on a lot of things, and I get a chance to play some small part in writing it.

As a result, there's a lot of debate going on about everything derby-related. I guess it comes with the territory. Being new and malleable, the sport is open to experimentation in a way that other sports simply aren't. There's going to be trial and error and adjustments to be made. Mix that with a lot of varying opinions, and you've got a good recipe for criticism.

When it comes to the sport itself, the most obvious adjustments come in the form of rules changes. It seems like everyone has an opinion on how to "fix" slow derby. Everyone seems to hate it when teams choose not to skate past the pivot line to bleed the clock or get an extra blocker back from the penalty box. There has also been a lot of discussion surrounding the idea that WFTDA might abolish minor penalties with the next rules update. Plenty of derby folk on the interwebs are more than happy to express their desire for WFTDA to adopt a "no minors" rules set. In fact, WFTDA actually beta tested that idea last year.

Both the "no minors" and "forced play" ideas have gained some traction. You can read various blogs about them elsewhere, so I'm not going to retread those debates here. In stead, I want to chime in on another common complaint about the current WFTDA rules set I've been seeing lately: The idea that power jams are somehow bad for roller derby.

The main criticism is essentially: "Power jams are too impactful on the game." No one can argue that power jams don't matter. Everyone has seen a 20-point swing result from a jammer penalty and completely change the complexion of a bout. The ever-present threat of this is undeniable. What is debatable is whether or not this is a bad thing.

Opponents of the current rules would say that it's bad for the sport that a critical power jam can change the outcome of a bout. I've seen several blog posts and internet comments that have put forth this argument. I could not disagree more.

Big plays are a part of a lot of different sports. They add excitement. In football, a deep pass to the end zone or a sudden interception return for a touchdown can be heart-stoppingly awesome. In baseball, a 3-run homer run can completely change a game. Hell, the simple threat of a big play making the difference helps keep a game interesting. Any bout within 20 or so points going into the last jam is not out of reach. It can make for some extremely dramatic finishes. Anyone who watched the end of the 2010 WFTDA championship bout knows what I'm talking about. Should we really want to change that?

I've also seen an argument that power jams usually only help the team in the lead. Jerry Seltzer wrote: "The concept that power jams will allow teams to come back from a big deficit rarely works; often they just allow the team that is leading to increase its lead."

Well, the fact is that when one team is winning by 100+ points, power jams are not to blame. One team is just a lot better than their opposition. Eliminating power jams is not going to make blowouts more interesting. The only thing that can fix that is the evolution of the sport. As the sport evolves, competition will become tighter, and match-ups will feature more similarly-skilled teams. In that setting, power jams will allow for more exciting bouts because more bouts will still be "within reach" in the final jam.

Another common criticism of the power jam is that it forces the officiating to affect the game to a larger degree. I won't argue with this, but I will point out that this is true of every team sport that uses a penalty system. In football, receivers are constantly trying to draw a big pass inference penalty. Basketball has been built around trying to draw fouls and get to the free-throw line. —And soccer... ESPN actually ran a commercial making fun of how soccer players fake injuries to draw penalties.

It's an inherent part of having a penalty system. There are always going to be strategies employed to try and force penalties to gain the advantage through the refs. It's unavoidable. I say we should embrace it. In my opinion, it's pretty awesome when that last blocker forces a track cut on the jammer and gives her team a big power jam. If you lessen the effect by shortening jammer penalties or eliminating them altogether, you just end up cheapening the value of good blockers.

The power jam rules debate really boils down to an argument between consistency and excitement. Do you want teams to win by playing a solid game throughout a bout, or do you want inconsistent teams to have a puncher's chance at the end? Obviously, there's a happy medium between those two aspects in any sport, but I would argue that the medium we currently have is pretty happy already.

I've been working on a a rather comprehensive stats study (the results of which you'll be seeing shortly) which includes the previously mentioned Points off Power Jams statistic. What I've found indicates that the average power jam doesn't have as much of an impact on a bout as many people assume. The words "power jam" automatically bring to mind an image of one team racking up numerous grand slams and completely taking over the bout.

The reality is that power jams like that are not very common in competitive bouts (and they simply don't matter at all in non-competitive bouts). Would you believe that in high-level, similarly-skilled match-ups, the average impact of a power jam is only about 10-12 points? Yes, there are some 20-point gougers, but there are just as many 5-point penalty kills. Just like with power plays in hockey, how well a team capitalizes on a power jam or kills a penalty can add another level of intrigue to the sport.

If you truly examine them, you'll find that power jams simply aren't the sport-destoying monsters that some people believe them to be. In fact, I would argue that they are part of what makes roller derby as awesome as it is.

Wednesday, February 15, 2012

Points Off Power Jams

Power jams in roller derby are a lot like turnovers in football. Both have a large impact on the outcome of a game. Both often trigger momentum shifts that can rally one team while leaving the other demoralized. Anyone who watches football can tell you that the announcers talk a lot about turnover differential and how it impacts the odds of winning. Turnovers make a big difference.

The same holds true for power jams in roller derby. If one team gets more power jams than their opponent, their chances of winning are obviously increased. Yes, there are a lot of mismatches in roller derby due to how young the sport is. Still, if 2 teams are similar in talent and skill, power jams can easily be the difference between victory and defeat.

One football stat that is often talked about alongside turnovers is "points off turnovers." Basically, it's the number of points a football team scores with the possessions immediately following turnovers. —The stat illustrates how much turnovers are effecting a game and how effectively a team is taking advantage of their opponent's mistakes. A team with 3 takeaways and 17 points off turnovers is really capitalizing on them. Conversely, a team that has 3 takeaways and only 3 points from them is wasting opportunities.

Enter "Points Off Power Jams" or PoPJ for short. Obviously, having a stat like this in roller derby could give you a lot of insight on how well a team is taking advantage of power jams and limiting the damage from them. Sounds great, right? Unfortunately, roller derby isn't as simple to break down as football. —Or maybe it's just that the sport of flat track roller derby hasn't been around long enough for people to really dissect it in this way.

The problem with tracking something like this is in differentiating which points resulted from the power jam and which points were just a result of normal play. You can't just look at the points or differential from full jams effected by jammer penalties. There are too many other factors in play. If a jammer gets double-slammed before going to the penalty box, 10 points from that jam are not a result of the power jam. Somewhere around 50% of jammer penalties also continue into the next jam. How do you take into account the new initial passes both jammers now need to complete before scoring?

Anyone can watch a bout and estimate a power jam's impact, but that's subjective. I hate stats that depend on interpretations because they're unreliable. What's needed is an objective set of rules to separate out the points scored as a result of the power jam from the points scored as a result of good pack play. Well, I've come up with a pretty good system that covers every scenario.

NOTE: For the sake of clarity and funness, let's call the jammer who is sent to the penalty box "Raskal Rae." The jammer who's scoring unopposed will be "Fannie Flash." Anyway, here are my rules for tracking PoPJ:

1. Jammer lap points are never counted. This is pretty straightforward. If Raskal Rae is lapped before going to the box, that point was not a result of the penalty. If she comes out of the box in front of Fannie Flash and is then passed, her point was the result of Fannie's blockers doing their job.
2. Jammer ghost points are always counted. Another easy one. As soon as Fannie Flash passes the first opposing blocker on a power jam, she gets the jammer point as well. Also, if Fannie is scoring but does not pass Raskal before she gets sent to the box, that 5th point is a result of the foul.
3. If Fannie Flash is between passes when Raskal Rae earns a penalty, PoPJ begins tracking immediately upon the foul being committed. This seems pretty simple, but it's important to spell it out this way. Technically, when a skater is sent to the penalty box, she is immediately off the track (and her ghost point is awarded if applicable). The time it takes Raskal to get to the penalty box is a direct result of the foul. Had the jam continued with her, we assume Raskal would have called it off to prevent any scoring from Fannie on her next pass. —And even if Raskal didn't have lead at the time or decided to let the jam continue, the points Raskal would have scored would have been offset by the points Fannie would have scored. The absence of Raskal scoring means a greater net gain for Fannie's team.
4. If Fannie Flash is in the middle of a scoring pass when Raskal Rae commits her foul, the points scored on that pass do NOT count towards the PoPJ (except for any jammer ghost point). Now we're getting technical. We are assuming that Fannie would have completed this scoring pass regardless of the penalty. Yes, this is a big assumption, but we need an objective way of tracking it. If you split apart scoring passes based on estimates, you start robbing the stat of its objectivity. The only option here is to not count the pass.
5. If Raskal Rae exits the penalty box on a scoring pass, PoPJ stops tracking points as soon as Raskal Rae enters the pack. Any points scored on a pass for Fannie Flash that is not COMPLETED prior to this are not counted (except for any jammer ghost point). The few seconds Fannie has to get out of the pack while Raskal is approaching are definitely a result of the foul. However, if both jammers end up in the pack at the same time, we view them as on parallel scoring passes. Because Raskal Rae's scoring pass is obviously post-penalty, we should view Fannie's pass the same way. Fannie Flash does have the option to call off the jam before Raskal gets to the pack, in which case the points from the unfinished pass should still be counted (because in that case Raskal never began a scoring pass). If Fannie fails to call off the jam before Raskal scores, we view it as a tactical decision. If Fannie did not have lead, that is the result of a error on Fannie's part (or her team's). Either way, if the scoring passes become parallel, we do not view the points scored as earned towards PoPJ.
6. If Raskal Rae exits the penalty box needing to complete an initial pass, PoPJ continues to track points scored by Fannie Flash, but only for the current / next pass (except for any jammer lap point). Fannie does not want to call off the jam right away because she's still scoring unopposed. She has 1 pass to give before Raskal scores, so we are giving her 1 pass to finish her scoring. This holds true even if Raskal completes an initial pass and begins scoring before Fannie completes this pass. Raskal's initial pass was parallel to the current/next pass for Fannie, so Fannie's pass still counts even if she is later lapped by Raskal while still in the middle of it (because Raskal's scoring pass is not parallel to it). If Fannie fails to call off the jam before Raskal scores, we view it as a tactical decision or an error by not getting lead (same as in #5).

The important thing to remember in all of this is that a scoring pass is either counted or it isn't. Again, the reason for this is to eliminate guesswork and build the stat around objective, factual data.

No stat is perfect. In reality, all power jam scoring passes are partially helped by the penalty and partially helped by the pack play. Hell, roller derby as a whole is a combination of any number of different variables at any given moment. It's like "butterfly effect" the sport. —But that's why I like experimenting with stats for it. There are so many possibilities when it comes to measuring how one thing effects another. I geek out about it. A stat like this is simply a slice of the sport that can help you look at a bout in a new way and maybe gain additional understanding.

Friday, February 3, 2012

Junior Derby and Building a Fan Base

It seems like roller derby is always fighting for attention. We live in a marketing-driven society, and cable television and the internet have brought a world of sports to our fingertips. —So it's no surprise that derby has to fight like hell just to avoid getting completely lost in the shuffle. Skaters have to put up flyers, make numerous appearances at community events, and partner with various sponsors just to get the word out. Despite all that effort, it can feel like they're still shouting in a vacuum. News media rarely acknowledges derby, and mainstream sports fans still view roller derby as a spectacle or kitsch.

As most leagues who have done a demographic survey can tell you, the vast majority of modern roller derby fans either know someone involved with roller derby or are involved themselves. Derby does not have a large following in part because it hasn't been around long enough to cultivate a fan base that rivals other sports. Beyond that, though, the stigma of the fake fights and staged outcomes of 70's roller derby seems to inhibit the sport's ability to be taken seriously. Derby remains very much a neglected sport despite every effort to be recognized. Meanwhile, networks like ESPN continue to cover professional bowling, competitive eating, and strongman competitions.

As roller derby continues to grow and evolve, it faces the question of how to break that barrier and take it's rightful place as a legitimate team sport in the American consciousness. The drum derby fans usually beat is: "Look at the WFTDA Big 5. You can't argue that this sport isn't athletic and competitive and sophisticated." While that argument is very true, it doesn't exactly convert many people dismissive of roller derby.

Perhaps the route to take with that kind of non-fan is actually at the other end of the spectrum. Junior derby has a big advantage that isn't being utilized to it's full potential. As people involved in roller derby, we tend to view junior derby as the next generation of skaters. I've heard it said on numerous occasions: "These kids are going to be the superstar skaters of tomorrow." While that is true, the more important and often overlooked statement is: "These kids are going to be the hardcore fan base of tomorrow."

Outside of roller derby, my favorite sport to watch is baseball. I grew up playing little league and watching the Twins win the World Series in 1987 and 1991. I didn't realize it at the time, but the bond I was developing with a simple summer pastime was the foundation for a lifelong obsession. I love baseball in a way that I honestly can't ever love roller derby. It's a connection to my youth that's so ingrained in me it's difficult to overstate. Roller derby simply does not have that kind of following because it hasn't had the opportunity to build those kinds of ties. Not yet at least.

I see the kids from the two local junior derby leagues (TCJRD and NERDy) at the local adult derby bouts all the time. They are far more into the action than the average fan. It's so endearing to seem them geek out about a star pass or an apex jump. They relate to the sport in a way that adult fans cannot. What's probably just as important as that is the fact that they are introducing derby to friends and family members who otherwise would not pay attention to the sport. A non-fan, dismissive of roller derby, is far more likely to give the sport a chance when viewed from the junior derby angle. The juniors don't have to battle a memory of pro wrestling-ish antics in the past. Junior derby is automatically assumed to be pure.

Along with it's lack of the "fake derby" stigma inhibiting it, junior roller derby is also undeniably cute. Crowds love it. Media loves it. It's attention-grabbing and approachable for anyone, even the conservative grandparents who do not like to step outside of their comfort zone. Suddenly, the crazy, far-out sport that they are not comfortable even thinking about is something interesting and new and fun for the whole family. That's what junior derby can do. —It can break down barriers for the sport and convince people to be more open minded towards it.

Junior derby is still relatively small when compared to the adult version that has driven it's inception. There's roughly 9 or 10 adult leagues for every junior roller derby program in existence. At some point, that needs to change. The future of the sport is not going to be 20-something or 30-something women (and men) finding a hobby later in life. It's going to be people who grew up with the sport and see it as part of who they've always been. That's how a sport's hardcore fan base is supposed to feel about it, and that's how derby is going to ensure that it doesn't disappear into the history books once more.

In my opinion, developing junior derby should be a goal of every modern derby league looking to secure it's future and a strong fan base. It could be something as simple as an occasional kids derby clinic (how it started here in Minnesota), but ultimately the best thing is for there to be a functioning junior derby league. Leagues should embrace this and invite the kids to skate pre-bout or at halftime. Some leagues even have junior derby programs as part of their own operation. Junior derby in any form is always good for adult derby.

There's a saturation point for adult derby out there somewhere. We haven't hit it yet, and it still seems to be a long way off, but you can be certain that it does exist. At some point, WFTDA and MRDA are going to stop growing. When we get there, modern roller derby is either going to hold steady or start fading. Junior derby holds more power than most people realize. It has the ability to secure the future of the sport in a way that the current adult version, which gets most of the attention, simply can't.

Wednesday, January 25, 2012

Jam Wins and Losses

Quick: What is the biggest hindrance to the usefulness of statistics in flat track roller derby?

Give up? The answer is sample size.

Let's look at a sport known for it's use of statistics: baseball. In baseball, an everyday player will come up to bat about 600 times over a 6-month season. A regular starting pitcher will face a lot more hitters than that: 800 is common, and several pitchers reach 900 each year. With such gigantic samples, it's easy to draw definable conclusions from even a single month's statistics. Once you get around 100 plate appearances, you can start evaluating and make adjustments throughout the season.

So how long does it take for a jammer to rack up 100 jams? One year, and that's if she's lucky. Unfortunately, you need to evaluate your team a lot more often than once a year. So most of your mid-year stat analysis is going to be based on insufficient sample sizes. Some of the data is pointing at a trend, but anomalous jams are throwing off the math. How do you tell a good differential built on consistency from a bad differential skewed by 1 or 2 big jams?

The answer is so simple that I can't imagine why I didn't think of tracking it earlier: Look at the jam win-loss record. In nearly every jam, both teams take the track with one goal in mind. No, that goal is not to get lead jammer; that's just a means to an end. Any team would let the opponent ultimately get lead jammer if it means that they can score 5 points before that happens. The goal is to win the jam. Tracking jam wins and jam losses is a simple way of seeing how often you are successful at achieving that goal.

Time to play make believe: You're evaluating a new jammer's performance in last Saturday's bout. Do you want her to be a regular part of the 3-jammer rotation in the upcoming tournament, or a secondary jammer who you can put in here and there to fill holes? Do you want to rely on her in a key situation to come through with a good jam?

Let's say the jammer in question had these 8 jam results last weekend: 0-4, 0-2, LJ 3-0, 0-0, LJ 24-0, 0-4, 0-9, LJ 0-0.

Her line would look like this: 3 for 8, 27 points, +8 differential. Pretty solid, eh? Not the best lead jam percentage, but still pretty good overall. A jammer you can count on in an important jam?

What about her jam wins and losses? 2 Jam Wins, 4 Jam Losses.

Well now, he have a red flag here. The win-loss record points to inconsistency. She scored the vast majority of her points in a single jam where she only had to skate laps while the opposing 2-pack was helpless. Apart from that jam, she struggled. Is this a jammer you want on the line in a tie game with 2:45 to play? The result of this jam could mean the difference between winning and losing the bout, and she appears to be twice as likely to lose the jam as she is to win it.

Obviously, I tailored the hypothetical situation here to make my point, but it still remains valid. A jammer with a positive differential who has won more jams than she has lost has been consistently good. A positive differential jammer who has lost jams more often than winning has probably gotten lucky. Of course, the other side of that is true as well. You could have a jammer with a negative differential who has more jam wins than jam losses and is being undervalued due to a couple bad jams.

Yes, there are several factors you should take into consideration before you choose who's in your main jammer rotation. (Which skaters are improving the fastest? Who is still recovering from an injury?) There are even more things you have think about when you decide who gets the star in a critical game situation. (How have each of your jammers been skating today? Who is rested and ready to go?) Still, I think consistency statistics like jam wins and jam losses can be helpful in evaluating skaters, lines, and teams as a whole.

Monday, January 23, 2012

Roller Derby and Civil Procedure

Here's a new one.

A University of South Carolina law professor is teaching a class about the parallels between lawyering and roller derby.

I'm not sure what to make of this. The seminar will have course credit attached to it, but it seems more like a really clever way to get people to watch roller derby and relate it to something they know. It also kind of seems like a Mickey Mouse course.

Not that I'm complaining by any means. I'm smiling as I write this, but it's a sly, "stealing from the cookie jar" kind of smile... Maybe I should have been a lawyer.

Anyway, I'll just choose to take this as further proof that roller derby is conquering the world.

Thursday, January 19, 2012

Initial Pack Strength/Advantage

Well, this is my first post so I might as well lead with what I know best: statistics. Gather 'round all ye derby stats geeks who happen onto this post somehow. I'd like to tell you about stat ideas I've come up with in an attempt to further the understanding of modern, flat track roller derby.

Let's start with a stat I call "Initial Pack Strength" or iPS. Basically, it's the number of pack skaters (pivot + blockers) on the track at the start of the jam. If you take the iPS for each team, you can also see who has the numbers advantage in the pack before the jammers are released. This is a related stat I call "Initial Pack Advantage" or iPA.

So, iPA = (your iPS) - (opponent's iPS). It's essentially a differential for the pack strength of both teams. +1 means you outnumber your opponent by 1 skater. -2 represents your pack being outnumbered by 2 blockers.

In tracking this, it has become very apparent to me that pack advantage matters a lot. I don't have any specific data ready to give you right now, but logic dictates that pack advantage = easier to succeed in roller derby. So, when a jammer grabs lead or even forces a 0-0 jam when her pack is outnumbered, it's a win. You can even take the total iPA in all of the jams and weigh it against her statistics to see just how well she did with what was dealt her.

"Jammer X only grabbed lead 3 out of 7 times, but she has a total iPA of -5. That's pretty damn good considering she was constantly outnumbered."

"Jammer Y may have gotten lead 7 of 10 times, but she was usually on the advantage. Her total iPA was +9, so a 70% lead jam percentage isn't anything special."

-But that kind of analysis begs the question: What is average? What can you realistically expect to get out of a pack advantage? Well, that's a question I've been thinking a lot about lately. I have a possible attempt to solve it in mind, but it will take a lot of work. If I decide to do it, you can expect a series of posts about it.

My main purpose for tracking these stats is to try and take the situation into account when analyzing skaters, lines, and jams. If your jammer takes lead when facing a 4-pack and only aided by a 2-pack, it's a big play. On the other side, if your pack surrenders lead with a +2 iPA, that's a definite problem.

Logically, you'd also think the best teams are the ones who can operate well when outnumbered. Every roller derby bout played by WFTDA rules sees an increase in penalties in the second half. The teams who manage their penalties well, and those who perform well with smaller packs, are the teams who succeed. Obviously, endurance and conditioning matter a lot to a team's performance in the second period. All things being equal though (such as intraleague season or high level tournament play), it might be more accurate to think of a team as "manages penalties and plays well short-handed" rather than the cliché: "second half team."

In my opinion, pack strength and advantage statistics are definitely worth looking at when trying to figure out how skaters or lines perform based on the situations they are in, and in examining why teams excel or struggle in the second period.