Record breaking 2.4 million PPV buys and competitive victory vs. HOF'er Oscar de la Hoya doesn't count? 5 KD's in domination of P4P listed Corrales doesn't count? Close battles in a clash of styles with the best LW of the decade in Castillo doesn't count? Generally someone's career defining fight is a very close competitive action fight with a fellow top fighter. Mayweather has virtually none. Which is a good thing for him. Castillo fights met those standards but was short on action and had no drama, plus people have very very very short term memories, soooooooo...