Ross Purrity was slower and had less power than Tyson and he KO'd Wlad!
So what does that mean?
Buster Douglas also had a better chin than Wlad.
And no Tyson wasn't in his prime in this fight. Tyson had already left his original trainer Kevin Rooney,spent time drinking,banging whores in Japan and doing no boxing training. Tyson was even dropped in sparring before the Douglas fight.
Tyson was already on the decline.