The guy was welterweight champion, then became middleweight champion after a long layoff. Where does he rank all time P4P?
Number 1. Lets be honest he was arguably number 1 anyways. But coming back after 4 years to drop and stop a current champion is out of this world. GSP by stoppage was incredibly long odds because no one saw it coming.
Beating Bisping isn't a great win, because it's Bisping. Bisping isn't that good. Had GSP beat Whitaker, Romero, or Souza that would have been really impressive, and you'd have no argument from me. If Mighty Mouse beats Dillashaw though, he's clearly number 1. He's in his athletic prime. He's more athletic, and more well rounded than GSP, and Dillashaw, is also a pound for pound guy, not a paper champion, that UFC protected and saved for GSP to have an easy entry into the middleweight division. Not a knock on GSP. GSP is like an MMA version of an older Hopkins. Not as fast, strong, or athletic as some of the young guns, but technically sound, with a great cage IQ, and makes the most out of the ability that he has.
Even Ali and Tyson weren't as good after a long layoff, what GSP accomplished is unheard of in combat sports. He's clearly the best ever, although an agruement can be made for Fedor.
Beating Bisping is a great win. I mean realistically who ranks above him as a MW? Silva Henderson Franklin Weidman Rockhold Souza Romero Whittaker Mousasi Shamrock This are the great MW guys not named Bisping. Does he belong on that list, if not he's only one tier down.