Who is the best interior defender in the NBA? What metrics would you use to answer that question?
Those are the existential questions in the crosshairs of a recent Kirk Goldsberry and Eric Weiss study, entitled, "The Dwight Effect: A New Ensemble of Interior Defense Analytics for the NBA."
Like errors and fielding percentage in baseball, and interceptions in football, it's inaccurate to ascribe a basketball player's defensive value to the number of blocks or steals he compiles over a given season. The best defenders often don't have the opportunity to rack up these stats; their mere presence around the rim is enough to produce second-guesses among opposing ball handlers.
In their first case study, Goldsberry and Weiss used shot location splits and shooting efficiency to judge the effectiveness of interior defenders located within 5 feet of the rim.
In their second case study, the duo looked at the location of interior defenders when a shot attempt occurs within 5 feet of the basket, along with the efficiencies of those shots.
The clear winner? Dwight Howard.
The loser? Let's just say that, for those who commence to eye-roll anytime someone refers to Serge Ibaka as an elite defender, this study salutes you.
From Goldsberry's analysis:
"We assert that ‘dominant' interior defense can manifest in two ways: reducing the shooting efficiency of opponents, and also reducing the shooting frequency of opponents. In terms of reducing efficiency, we found that Indiana's Roy Hibbert and Milwaukee's Larry Sanders were by far the most effective. We evaluated this by measuring the field goal percentage of close range shots when a qualifying interior defender was within 5 feet of the basket. Overall, NBA shooters make 49.7% of their field goal attempts when qualifying interior defender is within 5 feet of the basket; however, this number drops to 38% when either Hibbert or Sanders are within 5 feet."
And on Ibaka:
"Furthermore, out of centers who have faced at least 100 total shots in the basket proximity study, Serge Ibaka ranked last; when he is within 5 feet of the basket, opponents shot 74% of their shots in the close range area. This means that Ibaka is likely to be around any shot near the basket and suggests that while Ibaka leads the NBA in blocks per game, part of the reason is that he has many more "potential blocks" than almost any other defender."
Goldsberry also features a nifty visual breakdown (he's just the best at that) showing just how good Dr. Blocktopus is at altering a shooters course to the hoop. I won't post it here simply because his work deserves, at the very least, a click-through.
Additionally, the study found that Sanders leads the NBA in proximal field goal percentage (34.9% fg), defined as the opponents field goal percentage when the defender is within 5 feet of the attempted shot. Oddly enough, Andrea Bargnani finished second in this category (35.2% fg). And for what it's worth, Ekpe Udoh ranked 13th in proximal field goal percentage (46.2% fg) on shots taken within five feet of the rim.
Goldsberry and Weiss also discuss their limitations with this study (READ IT!), but at the very least, it quantifiably shows how quickly Sanders has progressed from a foul-happy young-ling to a less foul-happy defensive force of nature (primed for a pay raise) in less than a year.