I guess a lot depends on whether or not you view Fedor's losses as tarnishing his career. Obviously they don't mean much in the grand scheme of his career, but there's a long
way between not meaning much, and meaning nothing.
And it's a similar matter of opinion with regards to Anderson's lack of a Big Nog or Cro Cop. He doesn't have that defining fight, but with the exception of Chael, he has pretty much annihilated every one of his opponents. Prime Rich Franklin is no joke, but Anderson tooled him like he was nothing.
It's one of these things where it just depends what impresses you more - submitting Randleman immediately after getting dropped on your head, or not allowing yourself to get picked up in the first place.