Rocky didnt get "lazy". shit, he was in much better shape than he ever was in Rocky I and II. what happened to him and was explained in the movie is that Rocky just didnt care anymore about being the champ. he lost focus of what was important as a fighter. when the Rocky statue was unveiled, and Rocky announced at the ceremony that he was retiring, he was moving on with his life. away from boxing. then Clubber calls him out, riles him up by trying to turn his wife into a coalburner, then Rocky loses his shit and wants to fight him. but he's still lost his edge and thats why he lost because Clubber was hungry.
Ambiturner you know you fucked up when even chukzombi understands the movie better than you