The punch that landed on Roy in that fight would have ko'ed Calzaghe... Byron Mitchell knocked Calzaghe down. Tarver is a pretty big hitter who landed the hardest shot of his career against Roy at the exact wrong time for RJJ. It was a perfect punch that drops almost anyone without an a titanium jaw. I still think Roy hits harder than Calzaghe, but he just can't keep up with the pace... IF he can stay going forward I think Calzaghe would be fucked because he is too slow and has never had to deal with somebody faster than him. Prime Roy would have wrecked Calzaghe though.