We hear so much about his ROS, but a commentator during the match today said something I noticed in 2011 as well. To a certain extent, Djokovic is a rhythm player, but it's not just about rhythm. With a few forehand or backhand exchanges he often manages to feed to ball onto a very tight-angled flat trajectory onto or near the service line, drawing his opponent way off the court. I've never seen anyone do this with his precision. To me, his biggest strength (along with his ability to land the ball deep off the opponent's serve or otherwise) is a strategic/agility one whereby he can land the ball consistently in at those ridiculous angles, avoiding the net. Quite magical.