The Switching Hour: How defensive versatility is changing the NBA game
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LeBRON JAMES HUGGING the hardwood, sobbing with joy after winning Game 7 of last spring's NBA Finals? Yes, very memorable. But for statheads, another postseason image endures. It's the sight of Steven Adams, the 7-foot Khal Drogo look-alike, switching with astonishing dexterity and cutting off Steph Curry and Klay Thompson time and again in the Western Conference finals. The big Kiwi and his Oklahoma City mates didn't quite manage to take down the Warriors. But by relentlessly switching with Kevin Durant and their bigs, the Thunder did become the first team to slow down the Golden State death machine.
Indeed, OKC and Cleveland each showed that you need defensive versatility to counter Curry & Co.'s fast tempo, relentless movement and perimeter shooting. Now researchers are beginning to measure that skill, and smart teams are hunting for players who embody it.
While traditional defensive stats are limited to steals, blocks and rebounds, real-time tracking data allows us to more closely study the huge majority of plays that don't involve a change of possession. The NBA has been collecting such info at every game since 2013, and it provided it to the 210 students from across North America who participated in the league's first hackathon, in New York in September. Among the five finalists in the competition, two teams used the material to devise important new ways of analyzing defensive versatility.
Chris Jenness and Michael Wheelock of Rockefeller University looked at how many NBA defenders were able to hold opponents across various positions to effective field goal percentages of two points or more below average (minimum: 300 shots, 82 at any given position). They found that 26 percent of players, such as Houston's James Harden, can't defend even one position well. On the other hand, just under 10 percent of defenders are proficient against opponents at three or more positions. For instance, last year LeBron James held point guards to an eFG percentage of just 39 percent (versus a league average of 48 percent), shooting guards to 37 percent (versus 51 percent), small forwards to 42 percent (versus 53 percent) and power forwards to 45?percent (versus 49 percent). That's simple but powerful evidence of his amazing versatility.
Not so long ago, defenders who could lock down a single position had great value. But formalities such as whether you're a shooting guard or a power forward matter less today, as players must be ready to race outside to contest any opponent on the perimeter. That's where the work of Senthil Natarajan and Chris Pickard, two writers for Nylon Calculus, comes in. At the hackathon, they began by sorting players into statistical clusters based on 19 offensive metrics. Their analysis yielded five categories for describing scoring styles, whatever a player's position, so that "perimeter specialists" included Kyle Korver as well as Channing Frye. Then they examined how efficiently players defended against opponents of each type. Adams, for example, ranked No. 1 in the NBA at defending "skilled offensive bigs." Finally, they combined scores across categories to see how well players defended multiple styles.
Team Nylon named its metric the "defensive range adaptability" score, or DRAY for short, a nod to the NBA's most versatile defender, Draymond Green. Uniquely, Green ranked first or second in limiting opponents' scoring last season, whether he was facing 3-point specialists, skilled big men or versatile wings. Just as remarkably, Serge Ibaka, Durant and Adams all placed in the top five in DRAY. "The strength of the Thunder defense wasn't just their length," Natarajan says, "but the depth of their length and the amount of versatile defenders they could stack on the court." Unfortunately for OKC, Durant and Ibaka are gone now, and Victor Oladipo (49th in DRAY last season) and Ersan Ilyasova (166th) aren't likely to handle the kind of switching the Warriors will force even more often now that they have KD.
Looking for a team suited to battle the Warriors? Keep an eye on the Timberwolves, who won just 29 games last season but are building around versatility. Karl-Anthony Towns, a big man with superb mobility (36th in DRAY), could become one of the league's true unicorns. And Andrew Wiggins (15th) and Zach LaVine (113th) have the length and speed to defend anyone. To be sure, they haven't yet-but the group is young, and now Tom Thibodeau is in charge.
While Durant vs. his old team might get the most buzz this season, the Warriors against Minnesota's young corps will be fun-and instructive-for years to come.
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