I saw the knockout, just my opinion but I'll challenge anyone here to take the shot he did.
A hard shot to the side of the neck will drop anyone, never mind this 'chin' business, no one is immune as simple anatomy dictates that the amount of nerves and arteries in the region is the same for everyone.
Your nervous system has a massive shot, and closes your body down while it 'reboots'.
I don't have feelings for him either way, but he took a shot that would make an elephant weak at the knees, end of.