A Substitute for War

Basketball philosophy

Kevin Love, Dirk Nowitzki, Spencer Hawes, Andrea Bargnani and “Vertical” vs “Horizontal” rebounding

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Kevin Love, the 5th pick

Image via Wikipedia

Measuring an individual’s impact on team rebounding is a tricky, mystifying subject. In a way, rebounding is analogous to scoring in that it’s not as simple as measuring points per game and assigning impact from that alone. When a player takes a shot, he may be infringing on another player’s effectiveness or drawing enough defensive attention to improve it. Corey Maggette appears to get in the way of teammates by selfishly stopping the ball, Dirk Nowitzki appears to help teammates greatly by drawing defenders out of the paint. Even staticians favored stats like True Shooting %, measuring points per shot, can miss the whole picture.

Rebounding has even less statistics differentiating it. We have rebounds per game, Rebound %, plus/minus stats… and that’s about it. The rest we have to judge ourselves.

There are rebounders who have higher numbers on the boards who draw skepticism. Among those are Kevin Love, David Lee and Marcus Camby. The reason for this is that it looks like that instead of boxing out an opponent to get a rebound, they prefer to chase the ball to where it’s going to go. This is fine, but if they guess wrong, the man they’re not boxing out is open to get it. If they do get it, they may be taking a rebound a teammate was already going to get – thus despite being credited with the rebound, they are giving their team no additional value on the play. Thus the defensive rebound on this play is a misleading stat. On the other hand, if a player like Dirk Nowitzki shuts down his opposing PF’s bid to grab a rebound by boxing out and the ball is going towards him, but at the last moment a horizontally moving teammate grabs it, the player who grabbed it gets the rebounding credit, but it’s likely Dirk who deserved it.

An interesting comparison may come from pass protection in the NFL. A throw from the quarterback is in a way, analogous to a rebound. As in basketball, the defensive player should have the better position and is expected to properly cover and prevent the offensive player from catching it. The offensive receiver, like an offensive player in the NBA, still on occasion can break free to catch the pass or catch the offensive rebound. Now, in the NFL, effectiveness in pass protection is not about creating the most interceptions. It’s about preventing the offensive reception. Darrelle Revis is arguably the best cornerback and deep threat protector in the NFL, but the reason for this is that he shuts down offensive catches, not that he creates interceptions. Likewise, should the effectiveness of a defensive rebounder be tied to shutting down offensive rebounds rather than getting defensive rebounds? If you don’t get a defensive rebound individually, there’s still a high chance your team will retain the ball, especially if you do your job boxing out your man. But an offensive rebound means the entire team has failed rebounding on that possession. Your teammates cannot cover you in that situation. Hypothetically, let’s say there’s a player who has a 50% chance of getting a defensive rebound every possession that the ball is landing within reach, but his opponent has a 50% chance of getting the offensive rebound. This player may be putting up marvellous defensive rebounding stats, but is hurting his team because the negative value of the offensive rebounds against he created outweighed the positive value of the defensive rebounds created. Offensive rebounds are worse than defensive rebounds are good, because again, the latter can be covered by a teammate. Bringing it back to the NFL example, the cornerback who gambles constantly to get interceptions but allows many deep catches, is not doing his job as well as Darrelle Revis is. Furthermore, while in the NFL an interception is much more valuable than a mere prevented pass, in the NBA a defensive rebound via boxing out is worth exactly the same as one attained through leaving a man open to chase a ball. If anything the incentive to not gamble should be even higher in the NBA.

Now that doesn’t mean Love, Lee and Camby provide rebounding value. They do box out on occasion and a number of the rebounds they get, were ones that opponents would’ve gotten if they didn’t. But I believe it’s worth it to look at how each player rebounds, rather than just going by their numbers alone – for the same reason it’s worthwhile to ask how a player scores his points, rather than just that he does.

I believe one can differentiate between “Horizontal” and “Vertical” rebounding. By Horizontal Rebounding, I mean rebounds gotten as a result of moving on the floor to a place where a rebound is. By Vertical Rebounding, I mean rebounding as a result of not moving to the right spot, but having the reach or lift to get the ball from your rooted position. It would stand to reason that speed and reach determines which players do which. Kevin Love, I presume is a horizontal rebounder due to an undersized PF size and non exceptional vertical lift. Love of course averaged an incredible 15.2 rebounds last year despite this. Dirk Nowitzki seems as good a choice as any for a vertical rebounder, at a legitimate 7 feet and not as much need to move around when the rebounds come. Now here’s some interesting points:

Of Kevin Love‘s 15.2 rebounds per game in the 2010-2011 season, 10.7 (70.4%) were defensive rebounds, 4.5 (29.6%) were offensive rebounds. Of Dirk Nowitkzi’s 7.0 rebounds per game in 2010-2011, 6.3 (90%) were defensive rebounds, leaving 0.7 (10%) for offensive rebounds. Quite a significant difference between the two players.

Now the Timberwolves in 2010-2011 ranked 2nd overall in ORB% and 16th in DRB%. The Mavericks ranked 26th in ORB% and 7th in DRB%.

Is simply using these two player and their team results too small a sample size to draw conclusions from? Of course. I’d like to see other statistic analysis of tall and slow rebounders vs fast and quick ones, but here’s what I personally think. Horizontal Rebounding should translate excellently on the offensive glass, since it’s not about position but beating your opponent to where the ball is going. Great vertical rebounders likely have more trouble on the offensive glass, without their rooted position.

As a followup, I decided to look at the top 10 defensive rebound per game players in the league in 2010-2011 and their team DReb%s, with a minimum of 70 Gs:

1. Kevin Love – 10.7 DRPG (Wolves: 16th)

2. Dwight Howard – 10.1 (Magic: 1st)

3. Blake Griffin – 8.8 (Clippers: 19th)

4. Zach Randolph – 7.8 (Grizzlies: 21st)

5. Kevin Garnett – 7.7 – (Celtics: 9th)

6. Kris Humphries – 7.4 – (Nets: 14th)

7. Al Horford – 7.0 (Hawks: 10th)

8. Pau Gasol – 6.9 (Lakers: 22nd)

9. Al Jefferson – 6.8 (Jazz: 27th)

10. David Lee – 6.8 (Warriors: 30th)

Food for thought – Of the player’s who’s team DRTGs paled compared to their invidividual defensive rebound prowress, Griffin averaged 3.3 ORBs (27.2% of his total rebs) and the Clippers ranked 7th in ORB%. Randolph averaged 4.3 ORBs (35.2%) and the Grizzlies ranked 6th in ORB%. Gasol averaged 3.3 ORBs (32.4%) and the Lakers ranked 5th in ORB%. Jefferson averaged 2.9 ORB (29.9%) and the Jazz ranked 13th in ORB%. Lee averaged 3.0 ORB (30.6%) and the Warriors ranked 14th in ORB%. So we’ve got a pretty consistent trend of the players who’s defensive rebounds don’t show up as well in team stats, putting up great offensive rebound stats – and their teams having great offensive rebounding but suspiciously weak defensive rebounding.

If we’ve found players who’s rebounding stats and team impact looked like Love’s, can we find more who’s stats looked like Dirk’s? Now what I’m going to do is look at the top 10 defensive rebounding teams and the best DRB player on them, with their corresponding DRB per game rank in the league, with a minimum of 70 Gs played:

1. Orlando Magic – Dwight Howard – 10.1 (DRPG: #2)

2. New Orleans Hornets – Emeka Okafor – 6.3 (DRPG: #23)

3. Chicago Bulls – Carlos Boozer and Joakim Noah play 59 and 48 Gs respectively so neither meet requirement. Boozer ranks 8th in DRPG with 7.4, Noah 16th with 6.6.

4. Miami Heat – Chris Bosh – 6.5 (DRPG: #19)

5. Denver Nuggets – Nene Hilario – 5.7 (DRPG: #32)

6. Charlotte Bobcats – Kwame Brown ranks highest with 4.6 in 66 Gs which would rank 56th in DRPG if he qualified. Gerald Wallace posted 6.5 in 48 Gs for the Bobcats which would have ranked 19th

7. Milwaukee Bucks – Andrew Bogut plays 65 Gs/doesn’t qualify, but posts 8.0 DRPG, good for 4th if he did

8. Dallas Mavericks – Tyson Chandler – 6.6 (DRPG: #17)

9. Boston Celtics – Kevin Garnett – 7.7 (DRPG: #6)

10. Atlanta Hawks – Al Horford – 7.0 (DRPG: #10)

To make up for Chicago and Charlotte’s absence, here are #11 and #12:

11. San Antonio – Tim Duncan – 6.7 (DRPG: #16)

12. Philadelphia 76ers – Elton Brand – 5.4 (DRPG: #36)

Okafor grabs 3.2 ORBs of his 9.5 total, for a 33.6% that looks more fitting with the previous group. So not a good start to considering this coorelation. Bosh only grabs 1.8 ORBs of his 8.3 total, for a small 21.7%. Nene does 1.9 ORBs of 7.6 total, for a 25% number. Bogut does 3.1 ORBs per 11.1 total, for 27.9%. Chandler has 2.8 ORBs per 9.4 total for 29.8%. Horford has 2.4 ORBs per 9.4 total for 25.8%. Brand does 2.9 ORBs for 8.3 total, for a 34.9%. Duncan does 2.2 ORBs for 8.9 total, for a 24.7% number. In general, these numbers are much lower than the previous groups. There are a few exceptions in Okafor, Chandler and Brand who post a high percentage of their rebounds from ORBs but still anchor good defensive rebounding teams. Perhaps who they’re playing with helps explain it. Chandler of course plays with Dirk, the premeire example of a vertical, defensive rebound orientated rebounder. Okafor plays with David West, who averaged 2.2 ORBs a game of 7.6 total, a decent 28.9% ORB – but West is noteably a grounded player who uses his body to rebound. Brand likewise played with Spencer Hawes, who averaged1.6 ORBs of 5.7 total for a 28% number. Again, Hawes is tall and slow, a prototypical vertical rebounder.

Another thing I’d ask is, isn’t it weird that the Hornets could start Okafor, who ranks 23rd in DRPG, and West, who ranks 38th in DRPG, and find their way to 2nd overall in DRB%? Or that the Sixers could start Brand who ranks 36th in DRPG and Hawes who ranks 65th, and find their way to top 12 in the league. Those are insanely bad numbers for a starting frontcourt. Just how bad? If you took Andrea Bargnani and Eddy Curry‘s best DRB seasons, where they averaged 4.9 and 4.6 DRBs respectively, their combined total of 9.5 DRBs would be exactly the same as Brand and Hawes’ last season. One would think a starting frontcourt that atrociously bad at grabbing defensive rebounds would sink their team, even with good perimeter rebounders. Yet they made it to top 12. On the other hand, what about the Lakers having Pau Gasol ranking 11th in DRPG, Lamar Odom ranking 18th, and the 24th ranked player Andrew Bynum playing 54 Gs, yet they still found themselves in 22nd in DRB%. How is it that the Sixers can have their starting big men averaging 9.5 defensive rebounds combined and finish below that mammoth frontcourt? Or that Kevin Love averages 10.7 DRBs himself, more than Brand and Hawes combined, yet the Sixers are still the better defensive rebounding team than the Timberwolves? True, perimeter rebounders matter. But I have to think maybe, just maybe, there’s something else going on here. And perhaps players who aren’t grabbing any defensive rebounds but are sticking to their men like Spencer Hawes aren’t dragging down their teams as much as it’d seem, especially if Elton Brand is the horizontal rebounder I think he is, due to his smaller size and high offensive to defensive rebound ratio.

I’ll also say one more thing: As a Toronto Raptors loyalist, I’ve watched almost every game of Andrea Bargnani‘s career. My subjective perception of those games is, the defensive rebounding didn’t suffer when he entered games as much as you’d think. Even when he replaced an excellent statistical rebounder in Chris Bosh as he did often, it didn’t feel like the other team was about to go off on the offensive glass. The Raptors DRB% stats in his 5 seasons are 8th in 07 and 4th in 08 , both seasons splitting time with the vertical rebounder of all vertical rebounders, Rasho Nesterovic. They ranked 14th in 09 – You can take my word for this point as a message board and statistical hawker: The Raptors were plotting as the worst DRB% team in the league the first half of the year, then after trading Jermaine O’Neal for Shawn Marion, started plotting as literally the very best DRB% team in the league, eventually pushing that number up from 30th to 14th. My suspicion is that 2008-2009 Jermaine O’Neal had one of the least valuable rebounding seasons of all time, due to the combination of being a total horizontal rebounder and neglector of boxing out, instead choosing to pad his individual rebounds – and not only that, but having a terribly low 5.3 DRPG number in spite of that. The Raptors then ranked 23rd in 2010 and 24th in 2011 in DRB%, a significant dropoff. But if Bosh was there when the falloff happened in 2010 and Bargnani has been there the whole time. Perhaps neither Bosh’s departure or Bargnani’s presence can explain the dropoff in DRB%. A coaching change might. Under Jay Triano‘s 2 full seasons, they pulled in the 30th ranked DRTG in the league both seasons. Perhaps what we’ve seen the last two seasons is a complete and utter neglect of defensive duties, including defensive rebounding – and horizontal ball chasing on the defensive boards being the accepted norm. It will be interesting to see if a more defensive coach in Dwyane Casey will bump up the team’s DRB% numbers to 07-09 levels, even if Bargnani continues his horrid numbers on the boards.

I suppose if I was a greater statician, I would do a more comprehensive study of the players who are standout offensive rebounders and their effect on defensive rebounding, following Kevin Love and Zach Randolph‘s lead – and the players who are the opposite, taking a high percentage of defensive rebounds, like Dirk Nowitzki, Spencer Hawes, and Andrea Bargnani. I do suspect that vertical rebounding is more valuable than horizontal rebounding and that the key to great team rebounding is denial of offensive rebounds, rather than creating defensive rebounding – similar to pass protection in the NFL. But make your own conclusions.

*Statistics taken from ESPN.com and basketball-reference.com)

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4 Responses

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  1. A conceptualisation of “contested” against “uncontested” might be a useful measure, along with an on-off measure for team rebounding. Still, a good article about some of the pitfalls of raw numbers, which would probably hold true for most other raw stats, from scoring to blocks…

    Ravenred

    August 30, 2011 at 4:34 am

  2. This is interesting…I think there is great work to be done in analyzing rebounding impact.

    But you are leaving out a giant issue…rebounding is part of defense. It’s inseparable, both on the individual level and team level. That means when the defense is scrambled and someone has to help, the advantage can still be kept on the glass (there is now no one in place to block out the weakside defender). Turns out that OREB% does increase off of Opportunities Created.

    So bigs who have to rotate more playing with bad perimeter defenders will love the rebounding chances themselves. Overall teams who break down a lot will have weaker DREB% numbers, not necessarily because of anything inherent in boxing out or athleticism, but because they lost the battle before the shot was even up due to on-ball deficiencies.

    ElGee

    September 2, 2011 at 9:11 pm

  3. This is fantastic. I know you’re just using basic box score statistics, but you’re asking such probing questions and you’re getting so much out of it. It’s a cliche, but like all good research, it asks as many questions as it answers.

    Alex

    September 5, 2011 at 3:06 am

  4. […] Man to Man DefenseThe best starting 5 of all time – my picks1-3-1 Press: Question and AnswerKevin Love, Dirk Nowitzki, Spencer Hawes, Andrea Bargnani and “Vertical” vs “Horiz….broken_link, a.broken_link { text-decoration: line-through; } var analyticsFileTypes = ['']; var […]


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