Yeah, it wasn't a big punch at all. And his head hitting the canvas was the reason his body flexed from head to toe. I think it was a combo of an underdeveloped chin, genetics (some are predisposed to having a chin), and some left over shock from the first knock out by Tarver. He came back too quickly to fight after his first career knock out loss.
Nola, I too was a MMA guy. I kick boxed amatuer for 6 years, and then got into Jujistu. In MMA, I had 3 fights won 2 by submission, both knee bars, and one knock out. I lost by heel hook. Got out of it because, even when you win, you feel like you lost. But I love it to this day.