Herrmag is right...
Fedor hasn't fought anyone worth mentioning in the past 4-5 years. I don't think he fears anyone or is dodging fights, it's that in his mind his job is to fight, and it's his managers job to line up these fights. I don't think they had the same faith and confidence in him that he had in himself and didn't want to risk their cash cow losing.
In fact I would say that lack of quality opponents is what cost him against Werdum. He's almost out of touch fighting against the current wave of Heavyweight (a division he shouldn't be in anymore...should move down to LHW) fighters.
I wouldn't have had him top 10 before this, not because of any lack of talent, but because of quality of fights.
That being said, he's one of the greatest ever, without a doubt. He seems like a really nice guy if you watch enough stuff about him.