FiveThirtyEight has created a new defensive metric called DRAYMOND in an effort to find “a better way to evaluate NBA defense”. One of the bigger flaws in many other all-encompassing metrics is that it’s hard to find one that properly rates defense. FiveThirtyEight’s Nate Silver describes the issue perfectly:
Boston’s Kyrie Irving was regarded as a slightly above-average defender by RPM last year, for instance. But his opponents’ shooting data suggests he’s a big liability instead. On the other hand, Toronto’s Serge Ibaka was an excellent defender based on opponents’ shooting, whereas RPM regards him as just average.
Notice that Silver emphasizes opponents’ shooting — that’s a big part of their approach in developing DRAYMOND.
Basketball, in some sense, is fundamentally a shooting game. Shooting isn’t the only important action that takes place on a basketball court, obviously. But if no one kept track of who was taking shots and making buckets, we’d have, at best, an extremely fuzzy impression of which players were actually any good, even if we had access to all their other statistics.
But believe it or not, this had long been the situation when it came to measuring player defense. There are individual defensive statistics such as rebounds and steals, of course. But there’s no direct measure of shooting defense (other than blocks, which account for a relatively small fraction of missed shots). If an opponent gets hot against your team and shoots 53 for 91 en route to scoring 130 points, we know your team defended poorly in the aggregate, but we don’t know which players to blame.
That is, until a few years ago, when the NBA started publishing data on opponents’ shooting. Last regular season, for example, NBA Defensive Player of the Year Rudy Gobert defended a league-high 1,426 shots, according to motion tracking data by Second Spectrum, which identifies the nearest defender on every field goal attempt. Opponents made only 45 percent of those field goal attempts, well below the roughly 49 percent that Second Spectrum estimates “should” have gone in against average defense for a given distance to the basket.
You can check out Silver’s full introduction to DRAYMOND here. I am admittedly still trying to put it into full context and understanding myself.
But what immediately jumps out about the new metric is that since 2013-2014, among players who have played at least 10,000 possessions, Joel Embiid ranks as the 2nd most effective defender in the NBA according to DRAYMOND (he ranked 14th for the 2018-2019 season alone). By those parameters, the newly acquired Al Horford and Kyle O’Quinn rank in the top 25 since 2013-2014. Not bad!
I have to more thoroughly evaluate the player rankings according to DRAYMOND to know how much I trust it versus what I see on the court, but I still think this is a pretty noble and exciting endeavor by the folks over at FiveThirtyEight.