Not long ago I wrote that the Spurs' two major concerns this season, turnovers and defensive rebounding, were going to solve themselves over time. While I believe that still holds true for turnovers, rebounding is becoming more of a real problem. Right now the Spurs rank 23rd in the league in defensive rebound percentage, grabbing 71.3% of available defensive boards. Last season, they were the best team in the NBA in that category, pulling down 76% of available defensive rebounds. Something is decidedly different.
When looking at defensive rebounding numbers, the most logical thing to do is focus on the bigs. After all, that is one of their key responsibilities. Individually, Tim Duncan and DeJuan Blair seem to be doing a good job on the defensive boards with a stellar 30.2% and a solid 21.6% respectively. Boris Diaw and Tiago Splitter, however, have seen dramatic drops, with Diaw going from 16.7% to 11.2% and Splitter going from a respectable 21.8% to a paltry 13.6%. But those are individual numbers. What's really important is how well the team rebounds when those guys are on the court as opposed to off it.
Even though Diaw is the worst individual defensive rebounder of the bunch, he doesn't seem to hurt the team as much when he is on the court as Splitter, who sports a whopping -6.6% differential. So even though no one except for Blair seems to be helping the team rebound at a high enough level, the one who is struggling and hurting the team the most on the defensive boards is Tiago. Of course Diaw and Blair play most of their minutes with Duncan and either Jackson or Leonard, but as the prospective anchor of the second unit, Tiago is the one responsible for the poor numbers. At least that is what the numbers suggest. What they can't describe is why Tiago and the team are having such a hard time getting defensive boards. The answer is in the tape.
I reviewed every one of the 21 offensive rebounds the Spurs allowed in the last 3 games with Splitter on the court, and I saw three distinct situations.
Splitter is fouled
Both Mozgov and Turiaf committed obvious fouls on two offensive boards by pushing Tiago in the back with both arms. There is another situation in which Turiaf seems to push him, but it is not as clear. This situation only accounts for a couple of boards out of 21 total offensive boards allowed.
Splitter contests a jump shot in the perimeter and is out of the play
From time to time, Splitter is tasked with defending a perimeter-oriented big. In the last 3 games, he contested a 3 by Rasheed Wallace and an 20 footer by Blake Griffin. Against the Knicks, the other four Spurs were in position against Brewer, who somehow managed to steal the board. Against the Clippers, Deandre Jordan tapped it in over Duncan.
So that's 5 out of the 21 offensive rebounds allowed. Now what about the rest?
Splitter contests a shot in the paint and no one boxes out
Aside from the odd bad positioning by Tiago, I kept watching a variation of the same play over and over again: the Spurs perimeter defender funnels his guy to the paint, Splitter contests and forces a miss, and no one boxes out their own man or rotates to box out Splitter's man.
Now, it could be by design that Pop is asking guys to funnel their men to Splitter, considering the Spurs don't really have good perimeter defenders in the second unit. Unfortunately, they also don't have good defensive rebounders for the most part. Only Jackson, Leonard and, if you can believe it, Neal are rebounding over their career averages, even though with the Diaw-Splitter frontcourt there are a lot of boards to be had. When you couple that with Diaw's infuriating lack of commitment on the boards, it paints a pretty clear picture of why the team rebounds so poorly on defense with Tiago in the game. The lack of defensive rebounding has very little to do with Splitter's own flaws as a rebounder, but highlights even more concerns for the team about losing Jack and Kawhi.
So why was Splitter a good rebounder last season and not this one? The answers are simple: one, he played almost exclusively with Matt Bonner who, for all his many faults and limitations, is much more consistent than Diaw in sealing off his man and rotating on time, and two, Splitter is contesting much more aggressively now.
Tiago is averaging career highs in blocks per 36 minutes and block percentage, and while his numbers don't even come close to Duncan's, he is often helping the team protect the rim as well as Duncan does. Against the last three opponents, the Spurs allowed the same or lower percentage at the rim with Splitter on the court. The difference, other than the fact that Duncan is often surrounded by better rebounders and defenders, is the often underrated ability that Big Fun has to contest and remain in position to rebound.
When Splitter contests at the rim, he often needs to leave his feet and aggressively try to block shots in order to alter them. Duncan is longer and has better timing, which means he can remain standing or take a small jump. That allows Tim to recover much faster than Tiago. When both share the court and Duncan takes some of the shot contesting duties, Splitter's rebounding climbs and he grabs a decent 12 boards per 48 minutes.
The Spurs need to determine how they want Splitter to play. He can either try to contest less aggressively, remaining in good rebounding position, but likely allowing better looks at the rim, or he can keep doing what he's doing. For the more aggressive defense of Tiago to work, Pop needs to demand Diaw (or whichever big shares the court with Splitter) to step up his game and the wings to seal off their man and rotate to Tiago's on time. The other option is to change the strategy of allowing anyone who is remotely good at dribble penetration to get to the paint at will by playing better perimeter defense, but that is probably not realistic to expect that from all the Spurs guard and wings, considering both their talent level and their commitment to chasing opponents off the three-point line.
So while the Spurs' rebounding is a problem when Duncan sits, the one most responsible does not seem to be Splitter himself, but a combination of a seemingly faulty strategy and a complete lack of help from the other players on the floor, especially Diaw. Yet there is no need to panic; the Spurs have all the tools at their disposal to fix this situation. The team needs to get everyone on the same page and start rebounding as a unit consistently. The absence of both Leonard and Jackson is the perfect opportunity for the other wings to step up.