Mayweather let Cotto Hook him on the right side on purpose.
He knows Cotto's right hand is useless, so all he's doing is defending against his left hand. He only has one area of his body open against cotto's weak right hand, so that's the only area of his body he has to clench to catch the punch.
Which means he catches all of them. Body shots only really hurt when you're not ready for them.
Just writing this because I keep hearing about oh cotto caught mayweather cleanly so many time to the body, no he didn't. Well he got some good left hooks in but not a lot. I've never seen cotto hurt anybody with his right hand.
He's strictly a one handed fighter.