Just like in baseball, properly measuring defense has been the fly in the ointment of the NBA’s statistical revolution. Tracking blocks and steals is as incomplete of a defensive measure as counting errors in baseball, and +/- based stats have serious holes as well. Since good defense prevents things from happening instead of causing them to happen, it’s nearly impossible to measure as accurately as offense.
On Basketball Prospectus, numbers whiz Bradford Doolittle has taken a crack at a formula to determine the NBA’s best defenders by measuring opponent production against those players versus the opponent’s average production. Dwight Howard is atop the list, and the 2-5 spots are populated by some of the NBA’s best offensive players: Kobe Bryant, Kevin Durant, LeBron James, and Dwyane Wade. Doolittle thinks that their defensive ratings are so good because the skills that help them on offense also help them on defense, and that’s true.
I might add that all of those players spend most of the time conserving energy on defense instead of guarding the other team’s best perimeter players. Their athleticism makes it tough for great offensive players to score on them, but lesser threats have no chance. Ron Artest, Thabo Sefolosha, and Anthony Parker generally start the game taking the toughest perimeter assignments, with the superstars stepping up in crunch-time. That strategy is effective, but I think it skews the defensive numbers for the superstars in this formula.
I encourage you to check out the list; other surprises include Dirk Nowitzki a spot ahead of Kevin Garnett in the top-10, Caron Butler at 16, and Danilo Gallinari at 17. Measuring defense is a daunting task; I salute anyone making a real effort to try.