Defending the pick-and-roll against the San Antonio Spurs is really hard. There is so much diving to the basket, cutting from the weak side, and big-to-big passing that you can really get lost on where you should be defending next. When you do finally cover their pick-and-roll attack perfectly, sometimes they still kill you with it. 

Miami Heat backup center Chris Andersen recovered into the paint after some nice ball movement by the Spurs, and blocked a shot by Boris Diaw in the paint. Unfortunately, he blocked it right to Patty Mills, who still isn't on the Birdman's team. Birdman gets the fake assist on a shot against his team. 

So that's why guys like blocking the ball out of bounds...