Roy Jones Jr got knocked out by Glenn Johnson who Bernard Hopkins knocked out. What is your point? Moorer diminished his prime by drinking and gaining weight, very much like what Hatton did. It does not change the fact that he was undefeated in over 30 fights, something like 33 wins and 30 by KO.
OMG ever hear of Shavers, Cooney, Liston, Patterson, Marciano, Frazier, Louis, Baer, Dempsey, Tua for **** sakes the list goes on forever.
Calzaghe has a higher KO percentage than Jones Jr, would you consider their power comparable? Joe also had an insanely high KO percentage in 20+ fights... Are you calling him an all time P4P puncher?
KO percentage weighs heavily but thats not the only thing I look at. I look at who he knocked out. Moorer knocked out some guys who had never been knocked out before in their careers. Did Calzaghe do this? If Calzaghe was knocking out guys who have good chins then I'd say Calzaghe has power that compares to Jones. Jones had power too at 168 comparable to Moorer and Calzaghe to be fair.
You also have to look at how the knockouts took place... Were the guys knocked senseless, or were they too overwhelmed with work rate to fight back, forcing the ref to stop it. I think Prime Roy had more p4p punching power than Moorer, Calzaghe isn't even in their league with power, but did have decent power when he was younger. It was never elite in my opinion.