[h=1]Top five overrated rebounders[/h][h=3]Howard, Cousins among top glass-cleaners who post empty numbers
By Neil Paine | Basketball-Reference
ESPN INSIDER
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One of the most frustrating aspects of analyzing a sport with many moving parts and player interactions -- like basketball -- is that diminishing returns rear their ugly heads just about everywhere.
Unlike baseball, a sport in which the marginal value of a given action at the individual level is essentially the same at the team level -- upgrading to a new third baseman who hits 10 more home runs than the old one, for instance, will result in 10 more home runs for the team -- adding, say, a prolific individual rebounder does not necessarily mean the team will reap big benefits on the boards.
Why is this? The main reason is that the act of rebounding involves players competing not just with opponents but also with members of their own teams. There are only so many boards to go around on a team, and often seemingly productive rebounders rack up gaudy totals in part by "stealing" boards from teammates, rather than adding extra rebounds to their teams' bottom lines.
We can detect this phenomenon in a number of ways. First, just take a look at the greatest rebounding seasons of all time, and the impact they had on teammates' rebounding numbers.
Since the NBA-ABA merger in 1976-77, there have been 689 instances of a player logging at least 1,500 minutes for a single team in a season while grabbing at least 16 percent of available rebounds while on the floor. If diminishing returns aren't a big factor, we'd predict their teammates to have roughly average rebounding percentages. However, out of those 689 players, only three had teammates who collectively posted an above-average rebounding rate. This is either a remarkably improbable coincidence or strong evidence that at least some of the boards pulled down by big-time rebounders have been taken away from teammates, not opponents.
The phenomenon also occurs when examining the impact of adding a great rebounder to a team. Since the merger, the 165 NBA teams that added a player who met our prior qualifications only improved their rebound percentages by an average of 0.4 points, despite adding rebounders who were, on average, 7 percentage points better than average. In fact, 62 of those 165 teams (38 percent) failed to see their rebounding performance improve at all.
The following five players are examples of this phenomenon -- their individual rebounding numbers are impressive, but they don't seem to add much to their teams' rebounding performance when they're on the floor.
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[h=3]J.J. Hickson, Portland Trail Blazers[/h]
Superficially speaking, Hickson appears to be one of the league's best rebounders, averaging 10.8 boards per game (sixth-best in the NBA) with a 21.7 rebounding percentage (fourth-best). However, there's plenty of evidence that many of those rebounds have simply been stolen from his teammates, not opponents. Only Anderson Varejao and Reggie Evans have a bigger differential between their own rebounding rates and those of their teammates, but at least Varejao and Evans lead their teams to above-average rebound percentages while on the floor -- and improve their teams' rebounding when in the game. Despite Hickson's gaudy individual stats, the Blazers have a negative net rebound rate with him in the lineup, and they actually rebound at a better rate when he's not on the floor.
[h=3]Omer Asik, Houston Rockets[/h]When Houston picked up Asik in the offseason, the Rockets may have expected him to improve upon their 14th-ranked rebounding rate in 2011-12 (although we'd hope that Daryl Morey would know better). After all, Asik pulled down a monstrous 20.1 percent of available rebounds for Chicago last season, better than all other players aside from Marcus Camby and Dwight Howard. So surely he's had a big impact on Houston's rebounding performance this season, right? Not so much. With Asik in the fold for 2012-13, the Rockets rank just 16th in total rebound rate, virtually no different than their performance last season. Sure, Asik is again putting up impressive individual numbers, posting a gaudy 21.4 rebounding percentage, but it's hardly made any difference in the Rockets' bottom line -- they're barely rebounding at an above-average rate when he's on the floor.
[h=3]DeMarcus Cousins, Sacramento Kings[/h]
If Cousins hasn't already worn out his welcome with the Kings, he probably will before too long. That means he'll likely find himself on the trading block, an attractive target for a number of teams looking for a talented -- if troubled -- young big man. But buyers hoping to improve their rebounding with a potential 20-and-10 guy might want to beware, because Cousins has been stealing boards right and left this season. He has one of the league's biggest differentials versus his teammates' collective rebound rate, the Kings aren't rebounding anywhere near as well as we'd expect from their component players despite Cousins grabbing rebounds at the ninth-best rate in the league, and Sacramento has a negative-3.2 net rebounding percentage with Cousins on the floor.
[h=3]Dwight Howard, Los Angeles Lakers[/h]
Once upon a time, Howard was a legitimately dominant rebounder, but his performance with the Lakers this season calls into question just how much of his glass-cleaning in Orlando was actually attributable to his own rebounding skills. Howard's numbers have stayed fairly intact this season -- although his rebounding rate is down, it still ranks 10th in the NBA -- but he hasn't had anywhere near the impact you'd expect from a rebounder with his reputation. With Andrew Bynum (18.7 rebound percentage) a year ago, the Lakers were the league's second-best rebounding team; adding Howard and his eye-popping 21.9 rebound rate has translated to a four-spot drop in rebound ranking for L.A. Further, the Lakers are barely an above-average rebounding team with Howard on the floor, and they rebound significantly better when he isn't in the game.
[h=3]Al Jefferson, Utah Jazz[/h]
Jefferson has long been a practitioner of the art of empty rebounding numbers. Superficially, his 9.0 rpg average and 17.2 career rebound rate (30th-best in NBA history) might tempt you into thinking he's a premier glass-cleaner, but those numbers belie the underwhelming impact he's traditionally had on his teams' rebounding performances. Last year, researcher Evan Zamir looked at how players impact their teams' rebound rates (over the previous three seasons), accounting for quality of teammates and opponents. The stats show that for all of Jefferson's individual rebounding stats, he's made his teams softer on the glass on both ends of the floor. That trend has continued in 2012-13; Jefferson still has a major difference between his rebounding rate and that of his teammates, the Jazz aren't rebounding anywhere near as well as you'd predict given their component players, and Utah rebounds much, much worse with Jefferson in the game.
Rebounding is undoubtedly a valuable skill for a player to have, but only if it improves his team's bottom line. All too often, players who put up monster individual rebounding numbers aren't actually increasing their teams' rebound rates
By Neil Paine | Basketball-Reference
ESPN INSIDER
One of the most frustrating aspects of analyzing a sport with many moving parts and player interactions -- like basketball -- is that diminishing returns rear their ugly heads just about everywhere.
Unlike baseball, a sport in which the marginal value of a given action at the individual level is essentially the same at the team level -- upgrading to a new third baseman who hits 10 more home runs than the old one, for instance, will result in 10 more home runs for the team -- adding, say, a prolific individual rebounder does not necessarily mean the team will reap big benefits on the boards.
Why is this? The main reason is that the act of rebounding involves players competing not just with opponents but also with members of their own teams. There are only so many boards to go around on a team, and often seemingly productive rebounders rack up gaudy totals in part by "stealing" boards from teammates, rather than adding extra rebounds to their teams' bottom lines.
We can detect this phenomenon in a number of ways. First, just take a look at the greatest rebounding seasons of all time, and the impact they had on teammates' rebounding numbers.
Since the NBA-ABA merger in 1976-77, there have been 689 instances of a player logging at least 1,500 minutes for a single team in a season while grabbing at least 16 percent of available rebounds while on the floor. If diminishing returns aren't a big factor, we'd predict their teammates to have roughly average rebounding percentages. However, out of those 689 players, only three had teammates who collectively posted an above-average rebounding rate. This is either a remarkably improbable coincidence or strong evidence that at least some of the boards pulled down by big-time rebounders have been taken away from teammates, not opponents.
The phenomenon also occurs when examining the impact of adding a great rebounder to a team. Since the merger, the 165 NBA teams that added a player who met our prior qualifications only improved their rebound percentages by an average of 0.4 points, despite adding rebounders who were, on average, 7 percentage points better than average. In fact, 62 of those 165 teams (38 percent) failed to see their rebounding performance improve at all.
The following five players are examples of this phenomenon -- their individual rebounding numbers are impressive, but they don't seem to add much to their teams' rebounding performance when they're on the floor.
<offer></offer>
[h=3]J.J. Hickson, Portland Trail Blazers[/h]
Superficially speaking, Hickson appears to be one of the league's best rebounders, averaging 10.8 boards per game (sixth-best in the NBA) with a 21.7 rebounding percentage (fourth-best). However, there's plenty of evidence that many of those rebounds have simply been stolen from his teammates, not opponents. Only Anderson Varejao and Reggie Evans have a bigger differential between their own rebounding rates and those of their teammates, but at least Varejao and Evans lead their teams to above-average rebound percentages while on the floor -- and improve their teams' rebounding when in the game. Despite Hickson's gaudy individual stats, the Blazers have a negative net rebound rate with him in the lineup, and they actually rebound at a better rate when he's not on the floor.
[h=3]Omer Asik, Houston Rockets[/h]When Houston picked up Asik in the offseason, the Rockets may have expected him to improve upon their 14th-ranked rebounding rate in 2011-12 (although we'd hope that Daryl Morey would know better). After all, Asik pulled down a monstrous 20.1 percent of available rebounds for Chicago last season, better than all other players aside from Marcus Camby and Dwight Howard. So surely he's had a big impact on Houston's rebounding performance this season, right? Not so much. With Asik in the fold for 2012-13, the Rockets rank just 16th in total rebound rate, virtually no different than their performance last season. Sure, Asik is again putting up impressive individual numbers, posting a gaudy 21.4 rebounding percentage, but it's hardly made any difference in the Rockets' bottom line -- they're barely rebounding at an above-average rate when he's on the floor.
[h=3]DeMarcus Cousins, Sacramento Kings[/h]
If Cousins hasn't already worn out his welcome with the Kings, he probably will before too long. That means he'll likely find himself on the trading block, an attractive target for a number of teams looking for a talented -- if troubled -- young big man. But buyers hoping to improve their rebounding with a potential 20-and-10 guy might want to beware, because Cousins has been stealing boards right and left this season. He has one of the league's biggest differentials versus his teammates' collective rebound rate, the Kings aren't rebounding anywhere near as well as we'd expect from their component players despite Cousins grabbing rebounds at the ninth-best rate in the league, and Sacramento has a negative-3.2 net rebounding percentage with Cousins on the floor.
[h=3]Dwight Howard, Los Angeles Lakers[/h]
Once upon a time, Howard was a legitimately dominant rebounder, but his performance with the Lakers this season calls into question just how much of his glass-cleaning in Orlando was actually attributable to his own rebounding skills. Howard's numbers have stayed fairly intact this season -- although his rebounding rate is down, it still ranks 10th in the NBA -- but he hasn't had anywhere near the impact you'd expect from a rebounder with his reputation. With Andrew Bynum (18.7 rebound percentage) a year ago, the Lakers were the league's second-best rebounding team; adding Howard and his eye-popping 21.9 rebound rate has translated to a four-spot drop in rebound ranking for L.A. Further, the Lakers are barely an above-average rebounding team with Howard on the floor, and they rebound significantly better when he isn't in the game.
[h=3]Al Jefferson, Utah Jazz[/h]
Jefferson has long been a practitioner of the art of empty rebounding numbers. Superficially, his 9.0 rpg average and 17.2 career rebound rate (30th-best in NBA history) might tempt you into thinking he's a premier glass-cleaner, but those numbers belie the underwhelming impact he's traditionally had on his teams' rebounding performances. Last year, researcher Evan Zamir looked at how players impact their teams' rebound rates (over the previous three seasons), accounting for quality of teammates and opponents. The stats show that for all of Jefferson's individual rebounding stats, he's made his teams softer on the glass on both ends of the floor. That trend has continued in 2012-13; Jefferson still has a major difference between his rebounding rate and that of his teammates, the Jazz aren't rebounding anywhere near as well as you'd predict given their component players, and Utah rebounds much, much worse with Jefferson in the game.
Rebounding is undoubtedly a valuable skill for a player to have, but only if it improves his team's bottom line. All too often, players who put up monster individual rebounding numbers aren't actually increasing their teams' rebound rates
