If you watch a college basketball game this season, you will without a doubt hear that so and so team is outrebounding so and so team by a 30-18 margin. Furthermore, watching College Hoops Tonight (or whatever it’s called these days) on ESPN will without a doubt result in Digger Phelps or someone saying that a certain team can’t win the national championship because they get outrebounded too much. Our request to you is this:
Don’t listen. This is because rebounding margin is the most flawed stat out there. To illustrate this, let’s take a look at the Baylor Bears. Topical, since they played just last night. Baylor currently leads the country in rebounding margin, at +11.4 per game. But a closer look reveals why. Baylor forces turnovers on just 17.2% of their defensive possessions, good for 324th overall in the country. This means that the opposition has many more shots to shoot, which naturally results in a lot more available defensive rebounds. And, since defensive rebounds are easier to grab than offensive ones, it artificially inflates Baylor’s numbers. In fact, Baylor is only 67th in defensive rebounding when calculating the percentage of opponents’ misses that they grab, which is the most important.
As Beadlemania hero John Gasaway posits, rebounding is really two skills: offensive and defensive rebounding. Defensive rebounding is the best way to compare how good two different teams are on the glass, because everyone tries equally hard to get defensive rebounds.
Offensive rebounds, however, are another story. Hard as it may be to believe, some teams don’t really try to get offensive rebounds. Take Colorado under Jeff Bzdelik. The Buffs are far more concerned with getting back on defense, usually leaving only one guy down low to try to grab an offensive board. This is a result of wanting to limit possessions. To wit, Colorado is 333rd in offensive rebounding this year and was 342nd last year. Staying in the Big 12, Kansas State still leads the country in offensive rebounding, at 43.5% Thus, rebounding margin can penalize teams that don’t try to go after offensive rebounds with the same vigor as other teams. We can argue the merits of this strategy another day, but the fact remains these teams are penalized for no reason in rebounding margin.
I don’t think I even need to tell you the last one: pace. Obviously teams that play fast are going to take more shots, which will result in more misses, which will result in more rebounds available. Take the Texas Longhorns. Texas is 6th in rebounding margin at +6.2 per game, and although they do well on the offensive glass, they’re merely adequate on the defensive glass, where more rebounds are available. This high rebounding margin is due to the fact that they are the 5th fastest team in the country. Northern Iowa is 104th in rebounding margin at +2.8 per game. However, they are much better than Texas on the defensive glass, only allowing the opponents to rebound 27.5% of their misses. This is because Northern Iowa plays at the 343rd fastest pace in the country at 60.9 possessions per game.
So there you go. How to be a good team in rebounding margin: play fast, don’t force turnovers, miss quite a few of your shots. I don’t want to give that team credit for much of anything, do you?