Why would Mayweather use the shoulder roll to defend himself in MMA? You would have to be stupid to think he would fight exactly the same way and into a MMA fight trying to fight the same way he boxes. Mayweather is very natural, I hear he picked up all his boxing very easily, and the same basics go for all martial arts including boxing. PUnches are nearly the same, kicks are similar to punches. The ground game can easily be taught to a competitive level. Obviously he would be able to compete with the division A wrestlers on the ground, but he can do enough to not let them do anything when it is on the ground, and he can adjust and beat them standing up. I still think he would have more trouble with not wearing shoes than anything.