Going into this fight there was a general consensus that Floyd was finally fighting a legitimate threat, that Mosley had the assets to give Mayweather a fight, and that, at some point, "Sugar" would hit "Money" with something big and then we'd see what the Pretty Boy was made of. Turns out we were right, for two rounds.
The first round was what you'd expect, a feel out round that could go either way. Also from the first, you could sense that Mosley could control the fight and as soon as he relaxed and opened up, Floyd would have to fight back or fall.
The second started with the same sense of impending drama. Then, all of a sudden, Mosley dropped a mean right hand on Mayweather that knocked him halfway across the ring. For the rest of the round "Money" was on the run and in the last minute, Shane hit him with another evil right hand that nearly dropped everyone's favorite villain.
In between rounds, Mayweather was able to regain his composure and in the third made the adjustments needed to win the fight. Again, seemingly out of nowhere, Floyd figured out a fast, hard, lead right hand that he was able to hit Mosley with seemingly at will. Shane would come in, Floyd would drop that right and back him off.
From then on the fight was a case of a really good boxer-puncher getting out-classed by an absolutely exceptional boxer. Mosley couldn't find an opening for those big shots again, and Floyd, using his unreal speed and even more unreal timing, hit Mosley again and again with that right hand. So much so that in the eighth, ninth, and tenth, he had "Sugar" on the run. It was a magnificent display of skill, ability, and calm. Mayweather won the fight 119 - 109, 118-110, and 118-110.
So what does this mean? Is Shane now a used up, old man? No, not really. Shane was out classed, but he didn't look beat to hell. He just couldn't get off because of Mayweather's ability to control the tempo. Will Shane fight again? Hopefully. Will he fight at the highest level of the sport in million-buy pay-per-views? Not likely.
How about the victor, do we now consider him the greatest? Are the lingering questions about his "fluffed up" record quieted since he has so thoroughly beaten a perceived threat? Not quite. Mayweather's gifts that make him special are unique. His speed and timing make him nearly impossible to hit, and his work ethic makes him impossible to wear down. But he doesn't quite have the killer instinct and power that we love in fighters. I will make this concession: He is the best welterweight since Ray Leonard and I put him in that class of 147-pounders who are just below Ray Robinson.
In the end I can't say enough about "Money's" ability and kudos to Mosley for hanging tough for twelve rounds against the best in the world. But ultimately, it was Floyd's unexpected weapon, his right hand, that spelled Mosley's doom.