There'd be some wicked jab exchanges in this one. I reckon McGirt is too good for Cotto, but I don't think it'd be one sided.
While I wouldn't go as far as to say they were two different levels, I think Buddy was clearly better than Cotto, and would win a convincing UD. McGirt had enough pop to hurt Cotto and keep him honest, and Cotto wasn't really a balls-to-the-wall pressure fighter that would stay on top of McGirt all night. Cotto was very tame-able. Buddy was more skilled, more adaptable, and had a higher ring IQ. Thing is, neither one of them had all time great stamina, but I even think McGirt has the edge there.
consider how well Cotto did against PBF. the performance he turned in that night would've been enough to beat mcgirt.
I always put more stock in actual wins, than doing well in a loss. But if thats the road you wanna go down.. McGirt did a helluva lot better against Whitaker than Cotto would have. Cotto doesn't have a win as impressive as the Brown fight. Brown was a top 10 p4p guy when McGirt schooled him.