He was a great win, not just good. And who cares if Chico Corrales was an ATG or not. He was the beast of the division at the time. And Mayweather beat him like he stole something. Dont try to diminish it by making it seem that Chico wasnt anything.
Imo I think people overrate Floyd's win over Chico, a great win at the time, and underrate Floyd's win over Genaro Hernandez. Imo Chicanito was a much better fighter than Chico was, his only losses when he was past his prime and moved up in weight to fight a prime Oscar and in his final fight a faded Chicanito lost to Floyd. In both fights, Chicanito still had some moments as if to let them know, yea, you're beating me kid, but I'm not getting beat that easy. And he did school both Oscar and Floyd for moments in the fights, and made them fight hard for it. Chicanito was a very good technical fighter, but he could wack. Not big punching power like Chico, but he hit hard enough for Oscar and Floyd to be wary of. Morales was definitely a better fighter, but at 122 and 126, not 130. 130 Chicanito was a better fighter than 130 Morales.