I agree that the point of the chin, creating a snap, is the optimal place to connect to get a knockout. But if you watched the Chad Dawson/Adonis Stevenson fight last night, you'll notice that getting caught on the upper jaw, where it connects to the skull behind the ear, is a pretty good spot to catch if you want to put a guy out. On top of it, it was the equivalent of a sucker punch in that Dawson didn't see it coming. Fighters will all tell you that those are the most dangerous.
"The best kind of pride is that which compels a man to do his best when no one is watching."