Do the Pieces Fit? Let’s Not Crown the San Antonio Spurs Prematurely

In the wake of a(nother) stellar summer, securing the services of LaMarcus Aldridge and David West while locking up Danny Green, Kawhi Leonard, Manu Ginobili and Tim Duncan to very team-friendly contracts[1. Soapbox time. By any reasonable estimation, the Spurs organization is a fantastic place to work. In every walk of life, people make money vs. quality of life decisions, and suggesting San Antonio is cheating somehow because they search out player interested in quality of life and have established an organizational culture where there are significant non-monetary benefits both on and off the floor is ludicrous. Especially in a league where it is more or less impossible to simply outspend the competition, gaining an advantage by being a place people like to work is laudable from both a human and competitive standpoint, and should be encouraged, not denigrated. I yield the remainder of my time back to the chair.], the reaction was instant and overwhelming. Despite Golden State bringing their entire core back from one of the more statistically and aesthetically dominant teams in recent memory, San Antonio has been installed as the Western Conference championship favorite for the coming season.

While that line is soft[1. As Talking Practice said on my podcast last week, the maximum bet limits available on those odds is very low and thus hasn’t been vetted by smart money.], it still seems like a case of irrational exuberance on big news. Certainly, Aldridge is a very good-to great player and a better player than the departed Tiago Splitter, but how much better will he make the team? Will his offensive skills provide additional value or merely redistribute possessions among the various stars? Will he be able to replicate Splitter’s defensive versatility? How much of an age-related decline will there be from Duncan, Ginobili and Tony Parker?

The last is a complete unknown at this point, while it is perfectly reasonable to suspect Gregg Popovich will find a way to make it all work offensively. But how about the defense?

After losing Splitter and Aron Baynes[2. Signed to a, shall we say, generous contract by Detroit.], San Antonio has a dearth of interior defense. On a per minute basis, Duncan remains one of the best rim protectors and overall defenders in the league. But what happens the during the 40% of the game Duncan sits or nights when he logs a DNP-Old? Aldridge has a well-known aversion to manning the center position, and during both regular seasons, has graded out as a slightly below average rim protector on my metric, largely because of how infrequently he manages to actually contest shots.

Over the past season, he’s contested around 29% of opponents’ field goal attempts at the rim while he’s on the floor. League average for big men has been between 37 and 38%. However, there has appeared to be something of a positional effect. Unsurprisingly, centers are around the rim more than power forwards. Understanding that positional designations aren’t hard and fast, last season the average center contested around 45% of available shots, while the average power forwards was closes to 33%. So even by power forward standards, Aldridge has been on the low side.

Still, he has logged some time at center and those minutes might be somewhat instructive in terms of what he might be able to bring to the table. While the public SportVU data doesn’t allow for this kind of lineup parsing, a combination of SportVU shot logs and play-by-play based on-off data can provide a rough approximation. It is not strictly an apples-to-apples comparison as multiple players can be credited with a contest in the “Defensive Impact” accounting[3. The data which forms the basis for my rim protection stats.], and a sizable proportion of shots which are blocked[4. 31% of all shots blocked within feet of the rim in 2014-15.] aren’t blocked by the closest defender, but rather by the second or third man into the play providing help.

That said, the correlation between shots contested at the rim and those contested as the primary defender is extremely high. As shown in the chart below, the correlation is just under 90% between Contest% as the primary defender and overall.

The relationship is weaker between FG% allowed in the two scenarios[2. Slightly over 50% correlation], but still evident.

In any event, the overlap is close enough to allow for some comparisons between the rim protection contributions of players who swing between both positions. The chart below shows the output of some of the most notable players who swing between the two big positions last season[5. By nature, it’s an approximation of position. Essentially, I’ve separated possessions where the players shared the floor with a player who is more nominally a center from those where they haven’t. For example, in Aldridge’s case, his “power forward” stats include time spent with Robin Lopez or Chris Kaman and the floor, whereas for Derrick Favors, I’ve assumed he’s playing center when not sharing the floor with either Rudy Gobert or Enes Kanter.]. For sake of context, the average big man contested roughly 30% of all available rim shots as the primary defender:

First of all, perhaps Greg Monroe’s reputation as a poor defender is overblown, in that in a more natural center role, he might show up better than in a system where he is asked to chase power forwards out to the arc and beyond.

Getting back to the Spurs, as the chart shows, Aldridge was on the low side in terms of Contest %, but not egregiously so, among this group while manning the power forward position. However, unlike the rest of the group, he saw no appreciable increase when sliding over to the center position. This is especially worrisome considering only Greg Monroe was more adept in this regard than was the man Aldridge is replacing in Tiago Splitter. With Duncan’s likely regular season minutes restrictions, this should be a cause of some alarm for San Antonio’s overall defense if they are completely lacking in another interior presence. All is not lost, Aldridge has shown more of an appetite for defending the rim in post-season play, upping his overall contest% (as either primary or secondary defender) to a more respectable 39.6% over the last two playoff years and holding opponents to only 42.8% shooting on those contests[5. League average on shots contested by bigs at the rim has been right around 50% each of the last two years.]. So perhaps he is able to use his length and bulk effectively to deter shots at the rim, and just prefers to avoid taking the night in, night out contact during the regular season, and the culture of high expectations in San Antonio will convince him to do so more regularly. But maybe not, and if not, a lot is riding on the legs of a player who will turn 40 during the first round of the playoffs in Duncan.