2-0 i forgot to say after your post even though i agree with most of what your saying theres the Marquez factor, Mayweather dominated a fighter that Manny had tons of problems with and most boxing experts thing Marquez won that 2nd fight
It makes no sense in comparing the two fights.
First of all: Mayweather fought Marquez at Welterweight. Marquez has done nothing at welterweight, and looked to be at his limit physically at 135. He had no business fighting at 147, and it showed. He looked horrible.
Second of all: Manny fought Marquez at Marquez' absolute best. Mayweather, you can argue fought him at his worst.
Besides, how they fared against each other has almost nothing to do with how they will fare against one another.
Styles make fights.
This can't be said enough. I'd still pick Miguel Cotto to beat Floyd Mayweather. He has the right style to do so, IMO.