Would Evander Holyfield, Mike Tyson, George Foreman, Ali, ...
We are talking about heavy weight boxers here. I completely agree that boxers below have absolutely no chance, someone like Mayweather will be gone in 10 seconds fighting someone his weight. Even heavy weight out boxers and technical like Ali is condemned to loose.
Brawlers and infighters like Mike Tyson is another story, most of you have only seen him in the mid 90's after his prison time. Frankly that guy is a joke, his best were between 84-88 that is the period that made him legendary. He is short and fast with short reach therefore he never fights for points and has a charge to reach his opponents that would make any UFC fighter proud. This is a guy who won 26 of his first 28 fights by knockout, 16 in the first round. A guy that knocked out opponents in his amateur days (wearing headgear, lighter gloves and only 3 rounds) and the only person to KO Larry Holmes champion at that time who never suffered a KO loss in 75 professional bouts.
Maybe he will loose 3 out of 4 times against the best UFC fighters but fighting Tyson at his best without gloves is suicide. He will break their skull with a good punch that connects, this guy needs a licence to kill fighting without gloves. Well yes this guy is an idiot, has a tattoo on his face and has a girl's voice but at his best was one of the greatest boxers of all time earning +$30 million per match (that is in the 80s) earned $80 million in 88 alone, that time gas cost what? Around 80 cents.
Videos you should watch if you only know him in the 90's:
YouTube - Mike Tyson
The second video includes his amateur KO, move forward to watch his KOs.
YouTube - The Best of Mike Tyson