Willie. Cauley. Bleepin'. Stein.
How did he do this? Here is something that will not really help you answer that question: stop this video right before he gets the ball. He's got both his feet just outside the dashed semi-circle. His momentum staggers. Amir Johnson, another large and athletic NBA player, is in his way. He's kind of far from the basket, all things considered. Okay, now start the video again.
And yet, somehow, HOLY CRAP.
Darren Collison doesn't help. He tosses one of those 'Oh, screw it, he'll get it" lobs. So Cauley-Stein has to catch the ball behind him, cock his arm, and then dunk. I'm not even sure he touches rim.
This right here is the leader in the clubhouse for dunk of the year.