I watched that last sequence about as many times than the Zapruder film was shown in JFK, and it's fascinating. Curry and Thompson did everything perfectly.
Coming upcourt, Thompson stays on Harden's right, keeping him from looping around and going right to the basket. Curry's stationed right at the three-point line, which stops Harden from pushing forward.
As Thompson gets into position on Harden's right, Curry actually blocks off Harden's right, as well, giving him the option of going down the left sideline for just a second -- but with Thompson ready to drop back and block off the path to the basket.
Harden darts left for just a second, but when he sees that Thompson is ready to drop back and that a teammate is arriving at the three-point line unguarded, he passes. If it were anyone but Howard, it would have been a perfect wide-open three.
Harden may not have even known who he was passing to at first -- or if he did, he was hoping Thompson would switch off him for even a second. But Thompson immediately notices that it's Howard and doesn't move to guard him at all and continues facing Harden. (That was the best part of the possession, to me. Nobody on GS really gave a shit about Howard at all.)
Brewer and Ariza are set up in the corners, guarded by Iguodala and Barnes, respectively. Terrence Jones camps out under the basket, with Green on him. Screws up the spacing, but keeps Green occupied, and Jones is probably thinking more about putting back a missed shot.
Barnes stays on Ariza the whole time, but once the ball heads to Howard, Iguodala heads for the lane, clogging it and ignoring Brewer, who probably wouldn't have much time for a catch-and-shoot, anyway.
Harden starts asking for the ball back before Howard even catches it. Howard gives it back to him, but Harden's still swarmed by Curry and Thompson.
Thompson briefly raises one arm, but after Harden dribbles once, he and Curry just stay low and poke at the ball, instead of trying to block a shot or get a hand in Harden's face. Could've backfired, if Harden raised up and shot, but it turned out to be the right move, since it kept him from even getting the shot off.
So much happening in under nine seconds. By the end of the game, I wanted Harden to pull it off, but it was just great to watch.
You forgot the best part of their defense, fouling the shit out of Harden knowing the refs would swallow their whistles.