Don't true all time great fighters usually lose when they are PAST their prime?

pacquiao has brutal knockout losses to torrecampo, 3K battery, losses to erick morales, and maybe has lost twice to juan manuel marquez. pacfans say manny is in the top 10 of all time greats, but you just don't see truly great fighters have their s handed to them at that point in their careers. i'm having trouble thinking of a great fighter with as many losses and controversial decisions at or near his peak than manny pacquiao. this only adds fuel to the steroid issues that will always follow manny pacquiao. look at ray leonard, for example he brawled with duran in a fight where some think he won, but we are talking about roberto duran, not some dude named 3K! hagler had early losses to tough philly fighters bobby watts and willie monroe, not some dude named rustico. marvin would also want to settle the marquez issue, and not say "this business is finished". most of ray robinson's 19 losses were when he was an old man.