Bute's chin.

The shot that the thunderous punching Golovkin dropped him with in the amateurs was an absolutely peach and Froch clocked him with a ridiculous array of flush power punches before he inevitably wilted. Froch has very heavy hands, someone with a glass chin would have hit the canvas or been out of there sooner than that if they got clean with as many big shots as he belabored him with.

Berrio was a massive puncher - voted the biggest puncher in the division by the Ring magazine in their annual end of year awards. He caught Bute with some big shots but Bute stood up to them well.

Pascal hurt Froch and dropped B-Hop but Bute took his shots pretty well.

Glen Johnson's right hands had Froch looking very nervous and uncomfortable at times in their fight, Bute stood up to them well.

Bika caught Bute with some big shots but nothing happened.

Miranda caught Bute with one or two big right hands but Bute took them well.

Zuniga was a pretty good puncher - he dropped the supposedly iron-jawed Pavlik.

Andrade was a good puncher. Bute was utterly exhausted when he hit the canvas in the dying seconds of the last round of their fight, after spending the preceding 10-11 rounds pounding the absolute **** out of his titanium-jawed foe.

Bute fought a lot of hard and decent punchers, some of whom are massive hitters, and he also fought pretty decent opposition on his way up too, a few of whom had dropped and hurt some very good and durable fighters.

Bute doesn't have a great chin but it's nowhere near as bad as many will try and have you believe. As has already been stated. He freezes briefly when he gets hit a lot of the time, which is more a symptom of a psychological flaw in his make up more than a serious problem with his chin, IMO. I think the loss against Golovkin likely left an indelible scar and has affected his self-confidence and made him question his ability to hold a good shot and the loss against Froch only further compounded that.