The reason he looked so stamina-wise and had such great stamina early is basically because he can make another fighter fight his pace that means he can rest when he wants come on when he wants just what he did against Margarito, and he held a lot early in that fight till about the mid rounds when he came on and finished it. Mayweather by taking the fight to him for the whole fight from the last minute of the 2nd round onward he never got that chance. When's the last time you saw a fighter coming forward on Shane Mosley and making him work and expend energy just to keep him off? No one.