The thing people need to realize about Floyd, and something that's always misconstrued, is that it's not about speed. Roy Jones was pure, unadulterated, twitch-y hand speed, and it's why once he slowed down just a hair, he started getting caught easily. While I do believe Floyd still has faster hands than Paq or Sergio, it's about anticipation based off his counter-punching.
He's not beating people to the punch because he's quicker, he's beating them because he's anticipating where it's coming from and getting there first. Whether it's the lead right hand he started finding Mosley & Ortiz with, or the uppercut he started catching Cotto with, once he finds something effective, he uses it to beat opponents to the spot.
People don't even fight Floyd the same way they do other boxers because of this. The approach is different because once in the ring, they have to take a more measured tactic, simply because Floyd's ability to block while staying in the pocket for a counter makes him much faster on the draw. Cotto is the perfect example, because had he approached the Manny fight with the same patience and technique he did with Floyd, the outcome may have been different. But he knows just like everybody else that Pac is coming out swinging wildly and he chose to engage that.
JMM is nowhere near as quick as Pac, but he touches him quite easily with the same technique. You multiply that ability by 100 with Floyd & I highly doubt either Sergio or Pac would even try to approach Floyd the same way they do everybody else once they see it firsthand. It just won't work.
On top of that, both Pac & Sergio have suspect chins IMO. People make a big deal about Floyd being caught by Mosley or Cotto, like it's the first time lol, it just lets me know they haven't been following him that long. Zab Judah, Chop Chop Corley and Manny Burton all caught Floyd with harder, cleaner shots. De La Hoya (who was just as big as JCC was last night) hit him with some good shots. His chin is probably the most underrated aspect of his game.