The tale of the tape isn't going to be a deciding factor in this bout. There isn't much of a gap between Hatton and Pacquiao in terms of size or weight. What's going to be the telling difference is their respective styles, and Pacquiao's quickness and conditioning.
Pacquiao is a physical specimen, he has two strong thoroughbred legs which has allowed him to go up in weight while maintaining his featherweight-like agility. His quick hands can spell trouble for Hatton, and his hairtrigger left counter can be especially punishing against Hatton's left hook.
I don't think that Mayweather Sr.'s involvement will change how Ricky Hatton fights. Ricky's newly given bag of tricks is going to be quickly forgotten once the punches start flying. It's unimaginable that Ricky Hatton is going to be outboxing Pacquiao. Once Hatton get's peppered by Pacquiao's quick punches he's going to fight his fight. Make no doubt about it, it's going to be a fight!