Fights where the result would have been different if the loser was in their prime

Marco Antonio Barrera destroys Con
Kostya Tszyu-Ricky Hatton
Vince Phillips-Ricky Hatton
Erik Morales-David Diaz (he won but he destroys him in his prime)
Oscar De La Hoya-Manny Pacneedle

Hagler-Leonard
Chavez-De la Hoya
Foreman-Holyfield
Holyfield-Ruiz (Prime Holyfield destroys him in all 3)