Archive for December, 2009


Derby 201 – Basic Derby Math

   Posted by: Bitches Bruze    in Promise

I realize for many the thought of math outside of school is scary and about as far from fun as one can get. But we use math all the time and great teams understand the concepts of basic math – simple addition, subtraction and rates – are the key to winning games.

In roller derby we call our games bouts, but that doesn’t really matter so much. Math is where it starts.

According to the Womens Flat Track Derby Association’s (WFTDA’s) rules, from the very beginning, the team with the most points at the end of the last jam wins.

Like most sports (but not all), its all about getting more points that your opponent.

How does a team get more points?

The key to answering that in a derby 201 mindset involves both understanding rates as well as understanding the role and importance of having the lead jammer in a jam.

Understanding Rates of Speed

At any given time there are two classes of skaters on the track – blockers and jammers.  As we learned in Derby 101, the blockers make up the pack. The jammers are not part of the pack and they score. Pretty simple, right?

We also know from derby 101 that the first time the jammers pass the pack, they get themselves in scoring position. After that first pass, they start scoring one point for each opponent they pass per lap. The “per lap” part we didn’t mention in 101. Each pass, the maximum number of points a jammer can earn is 5, as there are five opponents on the track. Normally, however, the maximum score is 4 because it isn’t that common a jammer will lap the opposing jammer, but it does happen.

Jammers don’t get to double up on points in a lap. What I mean by that is for each lap of the pack, they only get one point per opponent. There’s no advantage to passing someone, dropping back, and repassing – generally speaking.

Jammers also have the opportunity to get some easy points. Technically these are called NOTT (Not on the track) points. As soon as the jammer passes the first on the track opponent, she gets her points for passing everyone who is not on the track. Usually this refers to the skaters serving time in the penalty box. We call them NOTT because there are other times skaters are off the track or “out of play.” These situations include skaters who didn’t get on the track in time during the 30 second break, skaters off the track for injury, skaters heading to or from the penalty box and it also includes “out of play” blockers – those blockers who are more than 20′ ahead of or behind the pack.

Yeah, that’s a little hard to keep track of at first. This is one of the reasons jammers get their very own referees during the game to not only watch their penalties, but to track their points!

Yes, jammers score on skaters who are out of bounds when they are passed. Staying on the track and in the way of the opposing blocker is key to blocker success.

What does this have to do with rate of speed? Scoring mostly has to do with jammers skating faster than the pack. Since a jam can last no longer than 2 minutes, a jammer MUST skate one more lap plus a little more in the same time as the pack in order to score at all. Keep in mind the jammer starts 1/5 lap away from the blockers. If in 2 minutes the blockers skate 10 laps and the jammer skates 11.1 laps, the jammer has probably not scored any points. At the same time, if the blockers manage to keep the pack at 5 laps in 2 minutes and a jammer gets in 11.1 laps, that jammer has the potential to score in excess of 30 points.

Good, unopposed jammers can often make between 7 and 8 laps per minute on a flat track.

Sure, jammers have stars on their helmets and may often be considered the stars of the team because they score the points. They deserve that too because they do it all while being physically and positionally blocked. Without their blockers, they wouldn’t score any points and might even be scored upon.

Point Differential & Lead Jammer Status

Keeping the pack slower than the jammer rate isn’t the only goal of the blockers. I can think of only one other sport where players are playing offensively and defensively at the same time and that’s most billiard games. Let’s define roller derby then as the only contact sport where players play offensively and defensively at the same time.

If you’re a sports fan, take a moment to let that thought sink in. Imagine soccer or basketball with two balls! Or baseball with both teams literally alternating who is at bat each swing. Imagine having different teams on base, or having to choose whether to go for a goal or recover a pass.

At any given time each player – both on the track and off – is thinking “what can I do at this time to either increase my team’s score or keep my opponents from scoring?” Often times these thoughts are accompanied by weighing the merits of each choice. These decisions happen FAST!!!! For fans in the stands, unless you’ve really grasped this, it is this feature of derby which really propels it into a sport of its own.

Since every play affects the score for both teams, roller derby statistics are collected which calculate the +/- differential. The team that scores 1 – 0 each jam wins just as the team that scores 8-7 each jam. But the team that scores 1-0 tends to be less tired and more able to maintain a 1 point +/- differential in a jam than the one who has scoring in multiple passes in a jam.

This is where “lead jammer” really comes into play.

In derby 101 we say that the first jammer to legally pass all the blockers becomes lead jammer. This is a true statement, but doesn’t reflect the intricacies of that first pass. There’s only two clarification points to this:

1) The jammer got through first but did not legally pass every opponent. This usually happens when a jammer:

  • cuts the track boundaries around a single opponent
  • elbows an opponent as she goes past
  • makes some other illegal kind of block to pass an opponent

There are other reasons, but they are relatively obscure for Derby 201.

2) The jammer may repass anyone she didn’t pass legally to have legal passing status. This often happens and confuses the fans when the first jammer to get through got through way ahead of the opponent trapped in the pack. She may have even lapped the jammer but on her first pass, she went out of bounds while passing an opponent. While she’s through first and even free to score, her opponent can still become lead.

A jammer who gets caught up in the pack, and this usually looks like the jammer gets by 2 or 3 blockers and is hearded back into the pack for another beating by the front blockers, has plenty of opportunities to legally pass all her opponents. Often she passes them legally several times. She may even pass a couple of them illegally at some point. So long as she doesn’t incur a major penalty or four minors during that pass, she’s free to become lead jammer once she breaks free of the pack (which, according to the rules, is once she gets 20′ in front of the last blocker in the pack).

Some other fine but not obscure points to this:

1) A jammer who starts in the box may become lead jammer

2) A jammer who goes to the box during a jam may not be lead jammer that jam, and if she was lead, she loses that status

3) A jammer who goes out of bounds for any reason before she reaches the engagement zone (20′ behind the pack) the first time is ineligible to get the lead jammer status. This makes for some interesting jammer-on-jammer strategy some times.

Follow that so far? Good.

Once there is a lead jammer, that jammer/team has the ability to end the jam. There are a number of strategic reasons why a jammer would end the jam for her team:

  1. The jammer passed all the opposing blockers in her next pass and the opposing blocker is about to reach the pack. Calling off the jam makes the jam score 4-0. Win!
  2. The jammer is behind her opposing jammer and they are both reaching the back of the pack. Calling off the jam makes the jam score 0-0. While a tie, that’s WAY better than the opponent scoring first.
  3. The jammer’s been lapped and finally broke out of the pack. The jam score is 0-5 and the opposing jammer is hitting the back of the pack again. Realizing our 2 minutes is rapidly approaching, 0-5 is WAY better than 0-9 or 0-14, especially since our luck with getting through this pack wasn’t so good this time.

But the lead jammer doesn’t always want to call it off. Consider scenario 3 reversed! The lead jammer got through, passed everyone including the opposing jammer. This is the time the jammer needs to knuckle down and do it again. Its also probably the time her blockers need to see if they can keep the opposing jammer in the pack at an even slower speed so she can get as many laps in as possible. As a jammer, it is some times difficult to keep track of where the opposing team is in scoring and she depends on good communication from her bench and her team to know if she should keep skating or call it off.

There are also plenty of times where the opposing team has a jammer or blockers in the penalty box. Whether to take advantage of that now and keep scoring or start fresh and with the advantage in a new jam is too advanced for derby 201. Since flat track derby requires that initial pass before scoring, usually staying on the track is the best choice, but other things will weigh in and fans can contemplate these strategies.

Next I’ll talk about speed – which I’ve touched on a bit here, but I’ll go into more detail in the third installment of Derby 201.