No, the Spurs' Defense Isn't Actually Better Without Kawhi Leonard

You might not think that Kawhi Leonard is the best single defender in the NBA.

You might think it's Draymond Green or Rudy Gobert or any number of pocket picks from your favorite team.

But everyone has to agree that Leonard is one of the best defenders the NBA has to offer. The issue is that it's not really apparent in the San Antonio Spurs' overall defensive rating, their points allowed per 100 possessions, this season.

The Spurs are allowing 108.7 points per 100 possessions this season with Leonard on the floor, per Basketball-Reference. The league average is 107.0.

The bigger problem is that with Leonard on the bench, the Spurs are allowing just 94.5 points per 100 possessions.

What's Going On?

Good question!

So, based on defensive rating, the Spurs' defense clearly is worse with Leonard on the floor. Like, 14.2-points-per-100-possessions worse.

If you look at effective field goal percentage, which weights three-pointers being worth more than two-pointers, opponents shoot 52.1% against the Spurs while Leonard is playing.

The league average is 50.4%. No team allows a mark lower than 48.0%.

With Leonard on the bench, the Spurs are holding to opponents to an effective field goal percentage of 44.5%.

Yup. Something is off.

There's a bit of a vibe that the team is just getting out to slow starts defensively, but really, there's something bigger and more obvious going on.

Defending the Perimeter

So, three-point percentage against isn't really a reliable measure of defensive ability, according to a study by Ken Pomeroy. Let's keep that in mind in this next section.

With Leonard on the floor, opponents are making 38.4% of their three-point attempts, according to NBAWowy. The league average is 35.3%, per Basketball-Reference, and only two teams are converting at a higher rate at this point in the season.

While we aren't stopping here, it's probably fair to say that Leonard's on/off splits are a bit elevated because of such a high three-point percentage against. Also, let's not forget that the Spurs with Leonard are just 1.7 points worse per 100 possessions than the league average.

The real issue, at least to me, is that with Leonard off the floor, opponents are making -- wait for it -- 24.1% of their three-point attempts. No team is worse than 32.2% right now from beyond the arc.

Let that one sink in.

The Spurs are essentially playing against a collective team that clunks three-pointers much, much harder than any actual team would when Leonard is off the floor.

Another point of frustration (and confusion) in all of this is the fact that opponents are shooting just 21.4% from deep on corner threes when Leonard is resting. The league average on those shots is 38.2%. Opponents are shooting 34.5% from the corner with Leonard on the court, but just think about that for a second.

Opponents are making just more than 20% of corner threes against them when the league average is just shy of 40%. Again, per Pomeroy, three-point percentage against doesn't really tell us much.

According to Pomeroy, the better measure of perimeter defense is three-point attempt rate, the percentage of field goals that are taken from beyond the arc.

With Leonard on the floor, opponents attempt a three-pointer 28.9% of the time. Without him, that mark is 31.9%. The league average is 31.0%.

Even if we call that small difference in three-point attempt rate a wash, the Spurs are basically defending against a league-average three-point shooter when Leonard is on the floor, but teams are shooting like Ricky Rubio from deep when Leonard is on the bench.

Free Throw Woes

In terms of "free-throw defense," Leonard's stats are also suffering from some bad luck.

With Leonard on the court, the Spurs are allowing .220 free throw attempts per field goal attempt. The league-average rate is .272, and only two squads are getting to the line less frequently. So, the Spurs' Kawhi-led defense is doing its job deterring teams from getting to the line.

Unfortunately, opponents are converting 79.9% of attempts from the charity stripe, well north of the league average mark of 76.7%.

I'd bet you can guess where this is going.

With Leonard on the bench, the Spurs are allowing .334 free throw attempts per field goal attempt. Only the Los Angeles Clippers (.325) get to the line close to that often, and no other team is north of .309.

However, teams shoot just 74.0% from the stripe on those attempts.

That's really skewing the per-possession marks.

Make Your Own Luck

If we now consider the Four Factors of defense -- that is, after examining some tough luck for the Spurs with Leonard on the floor -- it's pretty safe to say the defense isn't actually better off without him.

I'm replacing free throws made per field goal attempt with free throw attempts per field goal attempt to help compensate for the discrepancy in free throw percentage with Leonard on and off the floor.

We already know that the unsustainably low three-point field goal percentage on a slightly-above-average number of attempts is weighing down the opponent's effective field goal percentage with Leonard off the floor.

But if we look past that discrepancy in effective field goal percentage, we see the team rebounds better with Leonard on the floor and denies free throw attempts at a stellar rate -- while the non-Leonard units allow them at pretty much a league-worst rate if viewed as an opposing team.

And, sure, the turnover rate is better without Leonard, but it's still above the league average of 12.9% with him on the floor.

Eventually, the Spurs' bench is going to give up three-pointers at a rate higher than 24.1%, and that'll help close the gap in these on/off splits.

This isn't to say the Spurs' defense is elite with Leonard on the floor or that the bench unit is bad by any means, but the team is still rebounding, generating turnovers, denying three-point attempts and free-throw attempts better than the league average.

And if their opponents start missing shots (and making them when he's on the bench) at a rate closer to the average, things will start to even out as the year progresses.