I agree, Cotto was great at that point in his career. But in another thread, right now, somebody is saying Cotto was "old" when he fought Pacquiao, even though he was 2 years younger and had great things ahead of him. It's a level of scrutiny that goes so far beyond what anybody from the past gets.
They are also calling Barrera old, even though Barrera was a big favorite and went on to beat the undefeated Prince Naseem several years after Pacquiao gave him his beatings.
My point by bringing up the size of Ali's opponents is not to diminish the wins, it's just to highlight the fact that when comparing p4p fighters with great resumes it's important to note that one guy fought in 8 weight classes, and the other guy was one of the bigger guys in the only weight class he ever fought in. Joe Frazier is a great fighter no matter what he weighed. But Ali, due to no fault of his own, was 4 inches taller, 10 pounds heavier, and had 7 inches of reach on the guy.
I'm not even 100% convinced that I think Pac should rank higher than Ali. I lean a bit in that direction, but I certainly wouldn't be the least bit bothered by seeing Pacquiao below Ali on any list. I think my main point here is that when we evaluate a modern fighter like Pacquiao with the same lack of scrutiny as some legendary fighters, a guy like Pacquiao starts stacking up really well.
My personal opinion is that we nitpick modern fighters to death, but we give legendary fighters the benefit of the doubt. I think some people don't want legendary fighters to be surpassed by modern legends, because legends of he past are almost mythicized at times. They are almost cemented in those top 10 p4p spots, no matter what.