Offensive Rebounding and the Celtics Off-Season
Posted by Zach Lowe on Jun 1, 2009
Ryan Parker is doing some serious freaking work over at his site, the Basketball Geek. Over the weekend, he posted a whole bunch of data measuring the likelihood of a team scoring a basket on a given possession based on how that possession began. In other words, how much more likely is a team to score after they force a turnover versus after giving up a two-point field goal?
Every piece of data he finds is interesting, even if some of them are expected. For instance: It’s not a surprise that teams score a lot more easily on a possession that begins with a steal or another kind of turnover, but the difference is really huge–nearly 20 percentage points in eFG% when compared to a possession that begins off an opponent’s made basket. One way to interpret that piece of data is to think that forcing turnovers on defense and avoiding them on offense are crucial to a team’s success. But then you look at the Celtics, a team that coughs the ball up at an alarming rate, or the Magic and the Spurs, teams that are “bad” at forcing turnovers but rarely commit them, and you begin to wonder if excelling at one end of the turnover spectrum is enough to win. Or you wonder how amazing the Suns offense could have been, considering they had the fifth-worst turnover rate in the league on offense and the tenth-worst rate of forcing them on defense.
There was one other way to begin a possession that had a really big impact on the likelihood of a hoop: Offensive rebounding. It was a clear #2 behind turnovers, and, interestingly, helped a team’s three-point percentage more than any other variable. (See the second graph). This makes sense, obviously–an ORB can lead to a quick put-back or a kick out for an open three while the defense is scrambling to react.
Which brings up a general question that stats people much smarter than I have been trying to answer for a long time: Are offensive rebounds more valuable than defensive rebounds? Or put another way: Are good offensive rebounders more valuable than good defensive rebounders?
The quick summary is that there appears to be some evidence that an offensive rebound might be a slightly more valuable thing for an individual to get than a defensive rebound, since one of your teammates is far more likely to grab that defensive board than the offensive board. (The smart people call this the Law of Diminishing Returns; if you want to learn more, click on the link at the beginning of the last paragraph).
Let’s finally bring this back to the Celtics’ off-season. We all agree they need two sign at least two–and ideally, three–big guys who can fill out the bench. That group may include one or both of Glen Davis and Leon Powe. Davis and Powe have obvious limitations as players, but they are both good to excellent at one thing: offensive rebounding. Powe ranked 1st in offensive rebounding rate among 81 forwards eligible for the scoring title; Big Baby ranked a solid 21st.
As I’ve written before, Davis’ rank there surprised me, because he’s an awful defensive rebounder. Perhaps the presence of a defensive-rebounding machine (KG) has a little to do with that, but the gap between Davis’ offensive rebounding and defensive rebounding is one of the largest in the NBA.
Do these ORB numbers mean the Celtics should make re-signing both guys a bigger priority than it already is?
Ideally, the answer would be “Hell, yes!” but, alas, reality intrudes. In Leon’s case, the reality is his newest knee injury. Will he be explosive enough after yet another surgery to remain an elite offensive rebounder?
In Baby’s case, the reality is money. If he wants the mid-level exception, the Celtics probably have to let him go. As I said last week (piggy-backing off of Roy Hobbs at CB), the C’s likely have about $10 million to spend this off-season, including the mid-level exception, which will be someplace between $5 and $5.5 million. Since the C’s can re-sign Davis without using the mid-level (they have his Early Bird rights), the best outcome for the C’s is to sign Davis for significantly less than the mid-level (maybe $3 or $3.5 million/year). Will he agree to that?
Just for fun, after the jump I’ll list the career and most-recent-season offensive rebounding rates for the free agent forwards (and one center) I like best. (And, obviously, many of these forwards are valuable because of skills other than defensive rebounding–we’re going to take a look at most of them in detail individually in the weeks to come).
Glen Davis: Career ORB%: 10.7; last season: 9.4
Leon Powe: Career: 15.2; last season: 15.1
Josh Childress: Career: 8.1; last season (2007-08 in Childress’ case): 9.0
Grant Hill: Career: 4.2 ; last season: 3.2
Marcin Gortat: Career/Last Season: 14.1 (Note: I’m not counting six games from ’07-08)
Ike Diogu: Career: 11.2 ; last season: 14.4
Matt Barnes: Career: 6.3 ; last season: 4.6
BIrdman: Career: 12.0 ; last season: 13.4
Trevor Ariza: Career: 7.8 last season: 6.4
Brandon Bass: Career: 9.2 last season: 9.5
Antonio McDyess: Career: 10.1; last season: 11.6