I don't think this is strictly true. Traditional footwork, advanced footwork, all manner of punches, bobbing, weaving and even shoulder rolls have all been proven as effective in MMA, and the shoulder roll was something most people didn't think would work for one reason or another (myself included) BUT most MMA fighters don't have basic punching mechanics down. They just swing for power. Petr Yan is a great example of how good and refined boxing can look in MMA (he's a ranked master of sport in Russia in boxing specifically) Perfect hip and shoulder torque 1, shift into southpaw on the 2, followed by a southpaw 2 I don't think there's really anything in boxing that doesn't work in MMA, it's just the context of how you use it that is different. Like @DoctorTaco mentioned, MMA fights are mostly punching. I can count the amount of truly great kickers in MMA on just two hands, and if you're talking great thai clinch fighters, Matt Brown is the only good one I agree with you in that no one will be both Tyson and Gordon Ryan (although Garry Tonon seems to be making an honest attempt) - it's more that there is nothing stopping fighters from developing solid boxing fundamentals... they just don't. Most trainers too just aren't up to snuff, there are trainers who I know personally who will discount things as 'not going to work in MMA' even without actual knowledge of how to apply those things.