cotto's career prime was 140 because he was undefeated there.
but his physical prime was 147, he was draining himself to make 140 which probably weakened him a little and effected his ability to absorb punches.
and he was always a big 140 pounder.
yea he started taking losses at 147 but that's not because he wasn't at his best at that weight, its because the other guys (pacquaio, margarito) found ways to beat him.
Cotto was so good during that Pacquiao fight. Would that version of Cotto have walked through Spence and Crawford?
Nope….. He was never the same after Margarito took a couple bricks in the ring. Prime Cotto was at 140.