I disagree with all of you.... of course it was mental, Cotto was not pushing his punches at the end and they still all had snap on them, not to mention he was still moving and his knees were not buckling.. I'm not saying he wasnt exhausted but what prizefighter isint during a grueling battle... Cotto surrendered end of because he was done walking thru hell

Margarito snatched his heart and ate Cotto's will