I agree with the posters talking about the athletisim aspect of the game. Most boxers started at very young ages and the ones that make the big bucks (million+) weeded through a LOT of amateur and professional competition. Typically, money WILL attract the better athlete. Tyson in his prime is a better athlete than what we currently see overall in MMA. It is not a knock against MMA as I watch most events, I just know that MMA is a bit away from attracting the level of competition that boxing acquired over many many years.
MMA is still growing and still attracting new followers. In 20-50 years, it will be laughed at some of the "TUF" fighters that made their way to the prime stage and had minimal experience. Overall, Rich Franklin was a teacher not a fighter. You got guys like Sanchez, Kos(great wrestler), Bisping, Evans, etc that all made names by beating the ELITE of the division at some point. Now guys on the "Contender" that made it to the elite of boxing....got trashed. And we are talking about contenders that were 10-2, 22-0 (manfredo jr) 15-2 etc etc.
TO the topic, a prime tyson that learnes sub defense and TDD, would probably never need to use it. He was that powerful, fast, evasive and elusive that he would drop any MMA fighter 7 times out of 10 matches. His natural core power and speed have yet to be matched by any boxer/mma fighter. Watch his old training on youtube or the movie in theaters called "Tyson." His speed was blinding and we won his fights before he even threw a punch....people were that scared.