I don't know. I think Mosley was more physically gifted than Mayweather and also a bigger guy, as he was a huge lightweight who'd weigh 150 in some of those fights on fight night.

Mosley had amazing speed and could crack, but was fighting relatively weak opposition at 135. On the other hand, Castillo gave Mayweather all he could handle in the first bout, but Mosley and Castillo don't really fight alike.

I think Mayweather's boxing skills, defense, and intelligence would give Mosley fits. Mosley's always been overrated in terms of boxing skills, because he's fast. So people think he's some sort of great pure boxer, but he isn't, and never was. He's a speedy slugger who was at his best in the exchanges, and winged a lot of shots. He too often threw a pawing jab and left himself open down the middle. I can see Mayweather catching him down the middle with his accurate straight right hand and superior jab.

I also think it helps for Mayweather's sake if it's a couple fights into 135. Mayweather filled out nicely into the weight classes he fought in pre-147. Mayweather talked about hand and shoulder injuries in the first Castillo fight. Maybe it's true, maybe not, fighters always talk about injuries after the fact that it's hard to know when to take them seriously. But it was a jump in weight for Mayweather against a bigger guy in Castillo. Maybe the Mayweather against Ndou was better since he had 3 previous fights to be more adjusted to being a lightweight.