Lol why do you always so they have to go to the ground. You do know it's still considered a fight if they stand on their feet?
Of course. But the majority of real fights (I'm assuming he means outside of sports, out in the real world in a street fight or whatever) don't stay two guys standing on their feet throwing punches.
Do some? Yeah, of course. But most of them wind up being on the ground with people wrestling for position and control. Someone who can't do that, or isn't good at that (As I'm guessing most people would assume Mayweather is not good at that) would get destroyed on the ground.
You can't box from your back. You can fight from you back, and defend yourself, but all the skills that Mayweather possesses in boxing are null and void on the ground.
Which, in the cage, is exactly where a fight with McGregor, or anyone, for that matter would go against Mayweather. They'd just take him down, and beat on him on the ground.
Which is why I've said that Mayweather is simply not stupid enough to bother to get into the cage and even try it.