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.
Check out the video for a nice breakdown of the Spurs' defense -- it starts 30 seconds in.
You can check the full article from BBALLBREAKDOWN here. It's excellent and was done by our very own Jesus Gomez.
(And here's a YouTube link to a shorter video to watch in a separate window.)