Mayweather was doping, and knew Pacquiao's shoulder was injured.

Just look at his rather subdued celebration. He had just schooled Manny Pacquiao, in the fight of the century, the biggest fight since Tyson v Lewis.... and we dont see much emotion from Floyd. He was more happy over a win over Andre Berto... because in the Pacquiao win he knew that Pacquiao was injured and that he was doping. There was no sweetness in the victory! If you were to put Floyd on a lie detector test, I reckon the same thing will be revealed.