Is the 6'8 260 lbs Mount Whitaker, whose career-best wins were against Barret and Maskaev, too big for 5'11 190 lbs Floyd Patterson, who made a solid run but never beat a big guy? Size or class?
I'll go with class. Whitaker was a horrible, horrible fighter. Patterson had enough boxing ability to simply outclass him every round. The gap in speed is astronomical.
GOOFi (this was the actual way he spelled his name) was slow on feet but he punched pretty quick, mainly because he threw only slaps. Against most good heavyweights that would get him killed, but with Patterson's chin those slaps might be enough combined to the vast difference in reach