eh.... not gonna lie, I could definitely see McGregors leg kicks being a problem. People are used to seeing McG kick MMA guys who have trained for years to take, avoid, or check kicks.... and I think that makes him appear less impressive than he actually is in that area, and makes his kicks look less imposing and effective than they would be on opponents not trained for them. Dont get me wrong, you put Mc next to a Thai Boxer and obviously his kicks wont be up to par, but for MMA or a kickboxing fight against a boxer, I think they are good enough to cause problems. Go watch the Diaz 2 fight again, he landed some hard hard kicks that I garuntee you get into the mind of his opponents, and while obviously Diaz is a plodder, Mayweather will still have to be in kicking range to punch, and McG will land hard kicks.... I have sparred many times against lower tier kickboxers (succesful regional guys) and getting kicked sucks. Even checking kicks sucks if you havent put in the time to train properly conditioning yourself for them (and Im not sure a 2 month camp would suffice going from nothing to checking and absorbing hard kicks no problem) Im sure Mayweather could use his movement to keep McG from throwing a lot of them, but really... the guy is 40 years old, his mobility was declining already let alone the layoff, and hes going to be back in range everytime he wants to do anything in there.... he cant get in punching range without entering kicking range. He will take hard kicks to his lead leg. That all being said, I dont think they would probably decide the fight.... I do think they would play a considerable factor in it though. I still think Mayweather could beat G in a kickboxing fight, through boxing alone, if he trained smart and hard for a kickboxing match.
Aha. Here we go. This is the reason why bringing kicks into the equation makes Mayweather lose. You're asking Floyd to reconfigure his entire stance around a new threat he has never dealt with. Suddenly the angles and footwork PBF relies on and is used to are gone. Assuming he can work out a way to fight more or less as he did, there's a new problem - a leg has a greater reach than an arm. His touch n evade is going to be rather difficult when Conor has a weapon that can outreach him. Kicks bring a whole new dynamic to the fight. They don't even have to be hard. A relatively light tap to a lead leg can throw off one's balance, creating an opening for an attack with fists. But let's imagine that Floyd can work all of this out and become a relatively competent kickboxer. He's still got the problem that his shins aren't conditioned and Conor's are, and that even if they exchange shin kicks all night with equal effect, the guy that's going to be prejudiced the most by slowing down is Floyd, because his style is defensive and he needs speed.
Rick Roufus was really good. I remember watching him against another of my favourites, Le Banner. Roufus was old, getting fat and balding and Jerome was in his prime. Roufus landed all sorts of punishment on Jerome before the low kicks and size eventually took their toll. He had great timing and accuracy and a sweet spinning backfist.