This TrueHoop post is actually about PER, but this is too perfect to not mention:

The Celtics' defense is a friggin' symphony of subtlety. It humbles the NBA not because of one player doing one or two things that are obvious and measurable -- but because five players do the right combinations of big and little things, reading and reacting, as a unit. 

On just one play, you might see Kendrick Perkins blitzing a ball-handler in a way that's really convincing, inspiring an escape dribble that lets Paul Pierce catch up, taking the easy shots out of the pick and roll. All the while, Perkins never really committed, and before the ball-handler has even completed his escape, Perkins slides back to the paint, filling space, letting Kevin Garnett stay locked onto the talented big man. And now as the shot clock winds down, and the ball has been swung, Ray Allen gets his hands -- they're not really going to call a hand-check on that, are they? -- into his opponent's deadly right arm, forcing the star player left, to a spot on the floor where Rajon Rondo -- back turned, pretending he hasn't been noticing -- has been waiting all along to pounce. Tick tock tick tock.

That's a missed shot for the offense, that's a thing of beauty for the Celtics. That's basketball, in its vast complexity.