The basic fact of it from what I saw on the highlights, he just couldn't take the punches, and once he started shipping punches he couldn't stop the flow from continuing.

He got absolutely ruined in the first loss against Choi, and it's blasted his confidence and resilience. I didn't like him when he was fighting dirty on his way to the WBU title, but how bad he looks these days I have to feel sorry for him.