The Spurs’ excellent defense still has one glaring problem

Much has been made of the precipitous drop the Spurs defense made from great to very good this year. And understandably so. The 2015-16 squad was one of the stoutest defenses the league has ever seen, allowing 99 points per 100 possessions. That number is up over five points this season, as Gregg Popovich navigates year one without his wide-eyed sentinel manning the paint.

Tim Duncan’s retirement augured the end for San Antonio’s reputation as a defensive giant, one that now features the less defensively gifted Pau Gasol. Those who remained bullish on San Antonio’s chances pointed to the team’s two-time Defensive Player of the Year, Kawhi Leonard, and the franchise’s pedigree. But Leonard’s defensive metrics have been noisy at best (he continues to have the highest defensive rating on the team), and worrying at worst.

Let’s get this out of the way: Kawhi Leonard is still an elite defender, a long, strong dude who can at any moment turn into an eight-armed destroyer of possessions. He’s still providing crucial help defense and blowing up pick and rolls, while assuming a huge role on offense (he’s tied for the 10th highest usage rate in the NBA).

If we can tentatively agree that Leonard is great, then we have a decent starting point to see what could be pulling down the numbers of a guy who was second in the NBA in defensive win shares last season. The answer probably won’t surprise anyone who watches the games.

The D is improving, bit by bit

Despite a slight relapse in 2017, things are generally trending in the right direction for San Antonio after ranking outside the top 10 in defensive rating through the first month of the season. Pop has installed a solid scheme around limiting three-point looks and keeping opponents off the free-throw line that has them firmly within the top five right now.

The team began the year incorporating more switch-heavy schemes, usually in a madcap fever to chase teams off the three-point line. The system relied on quick decisions and constant communication that the new roster may not have been ready for, but there were still reasons to think it might work. Kawhi Leonard is a prototypical player in a switch-everything defense, and Danny Green isn’t bad either.

Against the Warriors, switching heavily worked. Golden State’s pass-happy attack couldn’t find the seams and didn’t really go after the mismatches that were created. It also didn’t hurt that it was their first game with Kevin Durant and were still working out how to be selectively selfish.

But against the Clippers, the scheme was fully exploited. LA’s sophisticated screen-setting and double actions had San Antonio heads spinning all night long, and the lasting image of their 24-point loss is probably what happened below. It turns out Chris Paul really likes being guarded by Pau!

Even when the Spurs avoided breakdowns, possessions would result in a veritable menu of mismatches for the Clippers to pick from.

Earlier this month, the Spurs blew out the Raptors, the league’s most efficient team in the pick and roll, according to NBA.com. While Toronto was finishing a lengthy road trip, San Antonio’s performance was night and day from what we saw against L.A., and a more disciplined, less switch-y defense had a lot to do with that.

The Spurs still switch now, but they’re letting opponents dictate less when and how they do it. One scheme they’ve turned to involves someone — usually Kawhi, Danny Green or Jonathon Simmons — shadowing the ball-handler while his teammates play normal man-defense.

Speaking of Jonathon Simmons

Simmons has been something of a revelation. He wasn’t a good defender last year, and he may not have even been an average one. He was poor closing out on shooters, prone to back-cuts and had one of the highest defensive ratings and defensive FG% on the team.

This year is a different story, as Pop has entrusted Simmons with more minutes and bigger responsibilities. He has the team’s second-best defensive rating (95.9) and his two-way contributions are a big reason why he’s made Kyle Anderson an afterthought in the rotation.

Kawhisolation doesn’t explain Leonard’s metrics dip

Leonard might have a much higher Defensive Real Plus Minus if he wasn’t part of a wing rotation with so many capable players. Four Spurs rank in the top 6 of the league among shooting guards, each with a higher DPRM than Leonard right now.

But it’s not just that one of the Klaw’s advanced stats is relatively low — it’s that he still owns the highest defensive rating of any rotation player at 105.4. A month ago, CBS Sports’ Matt Moore theorized this was representative of teams forcing action away from Leonard and stationing the man he’s guarding in the corner.

It’s true there have been individual possessions where teams have done so — Moore points out some good examples in his article — but most numbers show that Kawhi has remained as active on defense as ever. Last season, he defended an average of 9.4 shots per game; that number’s down just slightly, to 9.2, which suggests teams haven’t removed him from the equation. Beyond that, Leonard’s steal rate and block rate remain roughly what they have been in previous years.

Leonard is being used to offset the team’s worst lineups

The real issue is that Pop is, using his best defender to prop up his worst. Kawhi plays more minutes with Pau (828) and Parker (660) than anyone else on the team. One reason his numbers look bad relative to Tony and Pau (who have a 103.7 defensive rating): those two rarely play together without Kawhi on the floor. Out of the 638 minutes the pair have spent together on the floor, only 78 have been without Leonard.

That’s important, because as mediocre as Parker and Gasol are individually, their deficiencies are compounded when teams attack them at the same time.

The dreaded Parker-Gasol pick and roll defense

The first action almost every team seeks out against the Spurs’ starting five is attacking the combined 70 years of Tony Parker and Pau Gasol in a pick and roll. Know who’s really bad at guarding the pick and roll? Someone who’s giving up 1.25 points per possession to the PnR roll man? Pau Gasol. Know who’s in the bottom 10th percentile in defending the PnR ball-handler? Tony Parker.

Those numbers are independent of when they’re forced to guard the play together, a situation which regularly shows the two future Hall of Famers at their worst.

If the right matchup isn’t readily available, opponents haven’t had much difficulty in setting it up. There’s usually little Kawhi can do, even if he’s in the vicinity.

The Spurs have tried to make the Pau-Tony combination work, and the fact that they’re still piecing together a top-five defense is ridiculously impressive. Come playoff time, though, facing historically great offenses like Houston and Golden State, they will likely be forced to adjust.

Other lineups offer hope

In 126 minutes of playing together, the frontcourt trio of Leonard, Aldridge and Dedmon has a 95 defensive rating (and a 21.6 net rating). That’s a grouping we’ll very likely see more of in the postseason. Add Simmons to the mix (33 minutes thus far) and that defensive rating goes down to 92.1 (while the offensive rating jumps up to 128.1). That fifth player can be either Parker or Mills and the Spurs are fine defensively, while getting something different out of each PG on the offensive end.

Put Dedmon and/or Aldridge behind Kawhi and you see him get a lot more aggressive on pick and rolls -- similar to how he played with Duncan behind him — and that’s where he can really change games. If he doesn’t blow the initial play up with his length, strength and speed, the Spurs’ more mobile bigs are able to buy Leonard enough time to recover and make a play.

The defense as is will be enough for the Spurs to get by in the regular season — there are enough high-IQ players on the floor at all times, and the offense continues to jell each month. What will be interesting to see is how much Pop is willing to buck convention in the postseason, giving more time to less proven guys in the effort to let this very good Spurs team realize its potential.