As several opposing fan bases will tell you, Beverley has only one speed on the court -- full-bore. He might seem out of control at times, but his aggressiveness is a large part of his effectiveness. Point guards have a tendency to gamble with such a mentality, but Beverley strikes the perfect balance of risk and reward. He's like a tornado within a confined space when he attacks an opposing ballhandler, and his anticipation is without peer. It's the perfect mix of defensive traits for a point guard. If the Rockets take the next step as a title contender, a healthy Beverley will be a big reason why.
Robert Hanashiro-USA TODAY SportRobert Hanashiro
Jimmy Butler, SG/SF, Chicago Bulls
The same qualities that make Butler a proficient offensive player allow him to excel on defense. He's versatile, able to guard everyone from point guards to some power forwards. He's smart; once he's matched up with a player just a few times, he has a chessmaster's knowledge of his opponent's tendencies and preferences. And he's explosive. Though Butler is less likely to risk giving up position to hunt for a steal than some players on this list, he gets in passing lanes with ease when players telegraph their passes. One might expect the Bulls to take a step back on defense without Tom Thibodeau as coach, but Butler alone can help keep a defense afloat.
Draymond Green, SF/PF, Golden State Warriors
With apologies to teammates Klay Thompson and Andre Iguodala, we're rolling with Green as the best perimeter defender on the reigning NBA champs, mostly because he can guard players from anywhere. Take him out to the perimeter, and he'll man you up -- while knowing exactly where his help is at all times. Drag him to the post one-on-one because you think you have a size advantage, and you'll learn two things: He not only makes you uncomfortable by getting in your jersey, but he's also stronger than you are. You'll notice the latter fact as he inches you farther away from where you want to be. For someone who was supposedly undersized when he came into the league, he sure doesn't play anything like it.
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Tony Allen, SG, Memphis Grizzlies
It says a lot about Allen that he's the shortest player on this list, standing 6-foot-4. Yet he's still the second-best on-ball defender in the NBA, guarding everyone from Chris Paul to Kevin Durant, and doing it well. The league's shifting emphasis toward playing as many 3-point shooters as possible has reduced Allen's opportunities to play his brand of lockdown defense, sure. But when he gets an offensive player in his grasp, there is no escape. Allen's physical and aggressive style seems intuitive, but he's able to leverage his natural talent for stopping opposing scorers because of how mentally engaged he constantly remains on defense. If you were asked to name the NBA's best perimeter defender for the past five years, Allen would be an answer few could dispute.
Kawhi Leonard, SF, San Antonio Spurs
If Tim Duncan ever retires, the future of the Spurs defense is safe in Leonard's ridiculously large hands. The 2014 Finals MVP has no weaknesses as an on-ball defender. He's quick enough to stay in front of guards, strong enough to body up against bigger scoring forwards and long enough to contest anyone's shot. He also has a billiards player's sense of geometry and angles. No transition scoring opportunity is safe when Leonard is in pursuit, as he will find the right angle to come up with the block. He's studied with some of the best in San Antonio, sharpening his own instincts and knowledge to the point that he can bleed any offense dry in any way the Spurs ask. Oh, and with his massive paws, strength and cat-like quickness, he can strip even the very best ballhandlers in the league. Just pass it to someone else if he's on you.