The Spurs have built one of the best defensive teams in NBA history. This is mainly because of the genius of Gregg Popovich, but also the talents of Kawhi Leonard and Tim Duncan, players that execute the system to near perfection.
LaMarcus Aldridge, not usually associated with stellar defense, has also bought in, and looks engaged on both sides of the ball, something that wasn't always the case in Portland. Manu Ginobili and Patty Mills are also extremely energetic on defense, fueling the defense off the bench.