I'm far from a Lesnar fan but this is one fight the big lummox would win 98/100 times. 1) No TDD = kiss of doom against a wrestler, nevermind an insanely strong and large wrestler like Lesnar 2) Tyson's boxing stance is all wrong for MMA. Against a wrestler you're offering your lead leg for a single leg TD. Against a striker you're offering your lead leg to get beaten to a pulp by low kicks. 3) Lesnar didn't like getting hit, but he had enough of a chin on him to take bombs and keep fighting. He withstood a murderous assault from Carwin and came back to win. Tyson would do well to land something on him in the split second it would take to ground him. Once it hits the ground Brock will smother Tyson with his big oily pecs and ham-fist him into submission and it would look ugly. Boxing fans are deluding themselves that "one punch from a boxer" will take care of an MMA fighter. Some MMA guys can throw hands as hard as boxers - maybe harder because they don't have to worry about high level countering so much - and even with their ridiculously small gloves 1 punch KO's are not that common.
Tyson knocks this joke out early. The idea that this china-chinned WWF reject stands a chance against Iron Mike is beyond laughable. Another fragile MMA glass jaw shattered right quick, end of story.
Lesnar easily, Mike Tyson has never encountered a 6'3 265 pound NCAA Division 1 Heavyweight Champion. Lesnar wouldn't be dumb enough to stand with him like Tim Sylvia did with Ray Mercer. Lesnar would pound on Tyson and choke him out with little trouble. No Boxers are having success in MMA without actually committing to training in it and accepting the fact that they know nothing when it comes to grappling or other strikes not including punches.
Prime Mike would have struggled to win any of those early UFC tournaments imho, and Brock was on a completely different level to the guys in those. Theres always a punchers chance but at the end of the day its a much taller, much heavier, much stronger ex-div 1 national champ wrestler who was a UFC HW champ a bit over a decade ago, vs a 5'9ish, 220ish lb boxer who had his prime in the 80s at a time where he probably couldnt even conceive the notion of someone just taking him down and punching him out or submitting him, much less effectively defend against it.
Relative to MMA fighters today, sure. Relative to a pure boxer with no knowledge of grappling or kickboxing which a fair few of those guys were well versed in? no. Even Tank who was viewed as a glorified bar room brawler actually had a decent college wrestling background.