Advanced Stats 101: Rebounding
Last week’s Advanced Stats 101 studied two key defensive APBRmetrics in hopes of understanding how advanced statistics can propel the way we collectively think of defense. This week’s piece aims to shed similar light on rebounding, an aspect of the game that seems very straightforward but which careful consideration shows to be anything but.
It is apparent to any basketball fan the importance of controlling the boards. A solid rebounding team simply gives itself a better opportunity to win: if a team dominates the defensive glass, they limit the number of opportunities their opponent has to score, while strong offensive rebounding gives itself more possessions.
The most used way of measuring team rebounding success is to simply calculate total team rebounds by combining a team’s aggregate offensive and defensive rebounds. For last season, the best rebounding teams were:
Total Team Rebounds (2007-08)
1 Houston Rockets 3661
2 Seattle Supersonics 3659
3 Cleveland Cavaliers 3655
4 Los Angeles Lakers 3620
5 Denver Nuggets 3616
Contenders such as Dallas (9th), Boston (12th), and New Orleans (16th) were strong on the glass, whereas poor rebounding teams were primarily lottery-bound squads such as Miami, Sacramento, and Charlotte (the biggest exception to this is Toronto, who placed an alarmingly-low 28th in the total boards).
The question becomes, is there a better way to evaluate rebounding than with aggregate totals? Instead of being concerned with totals, which are dictated by things like pace and shooting percentage, is there a way to determine the probability that a team will get the next given rebound?
This is what Rebounding Rate (RR) aims to tell us. RR is the percentage of missed shots that a team rebounds. Since it is given as a percentage, it can be thought of as the total number of rebounds we can expect a team (or player) to grab out of a possible 100 available boards. The total team rebounding percentage is the average of its offensive and defensive rebounding percentages. The formulas for which are as follows:
Team OReb% = TmOReb / (TmOReb + OppDReb)
Team DReb% = TmDReb/ (TmDReb + OppOReb)
Team Reb% = (Team OReb% + Team DReb%)/2
Given these formulas, which teams had the highest success in terms of rebounding percentage? The top five were:
Team Total Rebound Pct
1 Cleveland Cavaliers 0.524
2 Houston Rockets 0.523
3 Utah Jazz 0.52
4 Boston Celtics 0.519
5 Philadelphia 76ers 0.517
We immediately see a shift: Seattle falls mightily (2nd to 13th), as do Los Angeles (4th to 9th) and Denver (5th to 21st). Conversely, we see other teams rise considerably, including Utah (24th to 3rd), Boston (12th to 4th) and Philadelphia (14th to 5th).
What do these radical jumps in the rankings tells us? For starters, it is clear that the total rebounding stats of teams like Los Angeles and Denver are a façade resulting from their faster pace and number of total possessions, which artificially inflate their total number of rebounds but do nothing to suggest they rebound at a higher rate.
Further, teams like Boston and San Antonio (23rd to 12th) make such dramatic jumps as a result of their rebounding efficiency. Their slower pace and effective defenses mean that there are fewer total rebounds to be had during their games, but they are highly effective at collecting those few boards that are available, meaning they have an even larger proportion of the harder-to-come-by possessions in their slower games. One need only think back to the Finals and then look at the effect this stat has specifically on Boston and Los Angeles to understand its ramifications
Having looked at team totals, it may be prudent to now explore Rebounding Rates for individual players to discover whether this metric is useful there as well.
For individual players, we generally use rebounds per game as the measure by which to evaluate effectiveness. The reason for this is clear, as it is simple and fast. The history of NBA rebounding leaders harkens back to legends of the sport like Wilt Chamberlain (11 rebounding titles), Bill Russell (averaged over 20 rebounds per game in 10 of 13 seasons), and Bob Pettit (career 16.2 rebounds per game).
While they may not measure up to these rebounding giants, last season’s leaders were:
Total Rebounds Per Game
1 Dwight Howard-ORL 14.2
2 Marcus Camby-DEN 13.1
3 Tyson Chandler-NOH 11.7
4 Tim Duncan-SAS 11.3
5 Al Jefferson-MIN 11.1
The reason we use rebounds per game is clear: it simple and fast. But Rebound Rate/Percentage is an even more accurate, and fair, way to evaluate rebounders by showing the percentage of all missed shots when they are in the game that they rebound.
Player Rebound Rate (RR = (100 x (Rebs x Tm Mins))/[Plyr Mins x (Tm Rebs + Opp Rebs)] give a better sense of effectiveness since it states the probability of a player grabbing a board while they are on the court instead of totals per game. The leaders last year were:
Total Rebound Pct
1 Dwight Howard-ORL 21.7
2 Joel Przybilla-POR 21
3 Marcus Camby-DEN 20.3
4 Chris Kaman-LAC 19.7
5 Tim Duncan-SAS 19.6
The top echelon of the list is similar to the traditional one, with Howard still dominating and Camby near behind. However the inclusion of Przybilla is noteworthy. Przybilla grabbed only 8.4 rebounds a game, but did so averaging under 24 minutes a contest. That he was able to haul in one of every five rebounds while he was on the court is most impressive indeed.
Alternatively, Al Jefferson falls sharply from 5th to 17th, in part because he has more opportunities via playing over 35 minutes a game.
Team and player rebounding percentage may also be isolated to show just defensive rebounding. This is useful because there is typically very little relation between offensive and defensive rebounding (at least on a team level). Teams that shoot a high percentage, are efficient with the ball, and play at a slower tempo, will all have low offensive rebounding totals since offensive rebounding depends heavily on how many shots a team misses or how committed they are to transition defense.
For that reason, most pundits agree that defensive rebounding is more important and gives a better barometer of great boarding teams. The best in this regard last season were:
Team Defensive Rebounding Pct
1 San Antonio Spurs 0.771
2 Cleveland Cavaliers 0.759
3 New Orleans Hornets 0.754
4 Toronto Raptors 0.751
5 Dallas Mavericks 0.75
If defensive rebounding is more important for teams, it should hold that it is for individual players as well. The league leader for individual player Defensive Rebounding Percentage were:
Defensive Rebound Pct
1 Dwight Howard-ORL 31.6
2 Marcus Camby-DEN 31.1
3 Chris Kaman-LAC 30
4 Tim Duncan-SAS 28.3
5 Carlos Boozer-UTA 27.7
Finally, for those pondering just how dominant Howard’s rebounding effectiveness was last year, his Defensive Rebounding Percentage from 2007-08 would place 11th on the All-Time Single Season list. The top five seasons are listed below (note that Dennis Rodman claims five of the ten best seasons ever).
All-Time Highest DRB% DRB% Season
1 Dennis Rodman 36.78 1992-93
2 Ben Wallace 34.95 2002-03
3 Bill Walton* 34.23 1977-78
4 Dennis Rodman 34.13 1991-92
5 Swen Nater 33.81 1979-80
Photo Credit: Icon Sports Media
This article was written by:
Trevor Smith - who has written 38 posts on Hoops Addict.
Trevor Smith is a management consultant living in Toronto, Ontario. He currently writes for HoopsAddict.com, and previously worked for NBA Cares. He is a graduate of Queen's University.