just too small, we've seen it in boxing many times. a guy with a good size advantage can really do a number on a smaller guy just because even glancing blows can hurt them and then the follow up with more glancing blows does the same, so , not as much skill needed to win. Patterson was probably more skilled than just about anyone he fought, no chin and too small though and kind of a headcase.
Patterson is the weakest of the great champs, but he was still great. Something like that.