Dennis Rodman explained why he was such a good rebounder. Rondo does the same. He watches the ball in flight and calculates where it will hit on the rim and heads for where it should come down.
What? When has that ever been the case or when has that ever really worked? Mixing lineups is the way to go. It's just that Karl still hasn't exactly figured out(or maybe he doesn't know how) a quality rotation.