Henry Cooper, Frazier, and some othjer guy I can't recall all put Ali on the deck. Tyson in his prime catches Ali and Ali ain't getting up. People forget how quick Tyson actually was, and how much sheer power his punches carried. Sure he turned into a psycho freak whackjob later on, but at his peak he was phenomenal. For a heavyweight he was small and light, yet he made 19 1st round knockouts, won his first world title aged 20 beating a 32 year old seasoned fighter, unified the belts, and was exciting as fuck to watch
Obviously opinions differ, but to write him off as some sort of no-hoper had he and Ali been around at the same time is well, wrong. So there ;)