Well he certianly hasnt got the iron chin of Magic Matthew Hatton, but it also should be said that brook hits better and harder than canelo. a direct quote from Mr Magic.
"Cotto's Chin Has Never Been Particularly Sturdy. . ." Nope. It sure hasn't. :deal I hope Alvarez can decimate that Chin. However, that's not a foregone conclusion in my opinion, since Cotto is going to be constantly on the move. He knows he can't the handle punishment.
And a direct quote from Lovemore N'dou too. So if Canelo does KO Cotto we can safely assume The Special One would
Over 10 rounds with plasterito, over 10 rounds with pacman... his chin is good... His skin though, it has a lot of wear and tear. Not worried about chin, worried about what happens if he is busted up....
His punch resistance has improved since he's gone up in weight. He does mark up bit, but then again, Canelo has showed some bruising in recent contests (Lara and Mayweather, specifically).
Would not surprise me. What I think will happen is Cotto will be on the run and likely get broken down by the mid rounds and Canelo will either win by Quit-job or ref or corner stopping fight.