3 things: 1) Naturally bigger (started fighting at 130, Pac started at 105), (2 inches taller), (5 inches in reach) 2) Incredibly accurate (Possibly the most accurate fighter in all of boxing), (especially since Manny is a little careless at times) 3) Pac has been in way too many wars. IMO the only people that can beat Mayweather are at 154 and up that are relatively big 5'10 plus that can work behind the jab. Someone like Winky Wright.
I knew that if Floyd made Manny miss Pac would slow down, I think he injured his right arm not before the fight but by missing punches