The Paradigm Shift: Floyd Mayweather beats Sugar Ray Robinson

No.

Robinson debut at 134 1/2 pounds, he started as a lightweight.
He didn't become a full welterweight until he'd had almost 30 fights.
He probably would have settled at 140 for a few years if that division was not defunct at the time.
There were no "3 or 4 divisions" for him to move through, to get to 147, like Floyd has.

So, actually, you could only argue 5 pound difference in starting weight, or ONE DIVISION larger by this era's standards.

But if you factor in that Robinson was weighing in on the same day, often on the evening of those fights, he's not at all bigger, perhaps the smaller man.

 

ray robinson stops floyd... if that same punch that mosley landed came from robinson, it would be lights out for the pretty boy