Stylistically I don't think people get how tailor made Manny is for Floyd. His bouncing, rhythm based style makes it so easy for Mayweather read when what Manny will be doing, and Floyd will figure him out in a couple of rounds and beat him to the punch for the rest of the fight ala Mosley. The biggest problem with Manny's style is that he loses balance, position at the end of a combination, and he needs a specific rhythm and distance to get off effectively, Marquez either stayed too close or too far away and Floyd would do the same thing, and he would pepper Pacquiao with lead right hands followed by the left hook then lots and lots of body shots. I think by the sixth round that Manny would be in a totally defensive shell where he would be too frustrated and try to load up more, but it would only make it easier for Floyd to beat him to the punch and hit him even more.

I just don't see Manny as his biggest challenge, IMO Bradley in a few fights will be a more significant threat because of how well rounded and skilled he is.