Hunter.
What are you talking about?
The size advantage enjoyed by Klitschko in nearly all of his fights is far greater than that enjoyed by Mayweather at any time in his career so far.
As a matter of fact as a fighter who has climbed weights Floyd is in fact naturally slighther than many opponents.

But that is not the primary difference between Floyd and Wladmir.
Floyd has been in some very entertaining scraps, fights against the likes of Castillo, Augustus and of course Chavez.
Those fights were give and take.

Have you ever seen Klitschko in a fight like that without getting knocked out?