Exploring Defender Distance in Analytical Analyses

Around this time last year, I was reading this piece in which Wizards coach Randy Whitman was quoted as saying the following in response to the analytics movement:

"We’re going to take open shots,” Wittman emphasized. “If a team wants to give us mid-range open shots, we’re going to take them. I’m going to tell a guy that has a wide-open 15-foot jumper to take three steps back and shoot a three? I’m not going to do that.” 

Basketball has an inherent inefficiency rooted in the fact that between a long two-pointer and a three-pointer there is only an approximately 8% percent decrease in expected field goal percentage versus a 50% increase in point value of the shot. Thus the expected points value per shot (field goal percentage timex point value of shot) is approximately 0.3 points higher on a three-pointer than a long two-pointer.

Prior to the 2014-15 season, however, the data did not (publicly) exist to add in an important dimension that Whitman touched on – that of the distance of the nearest defender to the field goal. With the NBA’s SportVU Player tracking data, it is now possible to add this dimension into the mix.

The league-wide results show that perhaps (depending on how one defines "wide open") Whitman should reconsider his position.

• On two-point mid-range shots (4 feet out to the three point line), when the defender is 3 to 6.9 feet away from the shooter, the expected points per field goal attempt at every distance interval is lower than the expected points per field goal on any three point field goal attempt, except for those that are BOTH very closely contested (0-2 ft) and very long (26+ ft) three point attempts.

• On two-point mid-range shots (4 feet out to the three point line), when the defender is 7+ feet away (which accounts for less than 3% of total FGA), those shots on average equate to 0.91 points per FGA, which is a lower expected point per field goal attempt than any three point field goal attempt, except for once again those that are BOTH very closely contested (0-2 ft) and very long (26+ ft) three point attempts.

Expected Points Per FGA Defender Distance Shot Distance 0 to 2.9 ft 3 to 6.9 ft >=7 ft 0-3 ft 1.07 1.37 1.69 4-6 ft 0.70 0.83 0.93 7-9 ft 0.74 0.84 1.04 10-12 ft 0.73 0.81 1.03 13-15 ft 0.70 0.82 0.97 16-18 ft 0.70 0.80 0.89 19-21 ft 0.67 0.77 0.90 22-25 ft 0.94 1.05 1.19 25+ ft 0.74 0.94 1.04

Distribution of shots Defender Distance Shot Distance 0 to 2.9 ft 3 to 6.9 ft >=7 ft 0-3 ft 17.08% 13.46% 0.84% 4-6 ft 4.81% 3.31% 0.06% 7-9 ft 2.80% 3.11% 0.09% 10-12 ft 1.46% 2.89% 0.16% 13-15 ft 0.99% 4.03% 0.47% 16-18 ft 1.01% 6.82% 1.34% 19-21 ft 0.67% 6.11% 1.49% 22-25 ft 1.20% 12.55% 4.73% 25+ ft 0.51% 6.09% 1.92%