The Spurs’ Defense and Three-Point Shot Prevention

During the first month of the season, the Spurs’ evolving offense has been a staple of the NBA conversation. Whether it’s the slower pace or the addition of LaMarcus Aldridge or the higher frequency of post-up plays from the elbows, San Antonio has given us many fascinating and substantive topics to discuss.

While their offensive adjustments have understandably garnered most of the attention, the Spurs’ defense has steadily produced impressive results. Their 93.4 defensive rating leads the average team by about nine points — one of their best differentials in over a decade. Even after accounting for the strength of opposing offenses, they remain atop the NBA. Of course, these numbers still need time to stabilize, but the early indications are definitely encouraging.

In some respects, the Spurs have simply maintained the defensive output that has served them well over the past few years. Take their opponents’ shot selection. When we focus on the defensive edition of Krishna’s Objective Basket Estimator (KOBE), we find that they’ve consistently ranked among the top teams in “forcing” difficult shots:

Since the 2013-14 season, Spurs’ opponents have averaged roughly 0.96 expected points per shot. San Antonio’s defense has made the top four each year, with the Chicago Bulls serving as the only other team who can claim this distinction[1. The 2015-16 KOBE numbers include all games through November 30. The Indiana Pacers and Portland Trailblazers also deserve recognition, since they’ve made the top five each year. With mere decimal points separating the teams, the rankings are admittedly less important than the overall performances.].

The Spurs’ low defensive KOBE is at least partly attributable to their prevention of three-point attempts. Currently, their opponents average just 19 of these shots per game, and they’re the only team allowing fewer than 20. They’ve led the NBA in this category for three straight years.

Naturally, the Spurs have driven their opponents to less efficient areas of the court. We can see this phenomenon reflected in their low “Moreyball” rate, with less than half of the shots that they allow occurring at the rim or behind the arc. Another way of looking at it is the ratio of mid-range to three-point attempts:

As discussed elsewhere, three-point attempts have overtaken the league, yet the Spurs’ defense has largely resisted the trend. They’ve kept opponents at 1.2 mid-range jumpers for every shot beyond the arc — about 0.3 above NBA average, which is similar to the previous two seasons. No other team has really come close this year:

It remains to be seen whether the Spurs can sustain this performance, especially when they square off against the Warriors and the Rockets. But it should be noted that they’ve already faced five of the top-ten teams in three-point attempts, holding them to an average of just 21 shots from downtown.[2. In particular, the Spurs allowed just 19 three-pointers against the Celtics and 17 three-pointers against the Hawks.] So they’ve shown that they can restrain some of the most prolific shooters.

More broadly, it’s always hard to discern the degree to which these numbers are influenced by defensive pressure or indicative of deliberate offensive strategies. But, while precise measurement may be out of reach for this post, the Spurs’ multi-year consistency is certainly a mark in their favor.