He had one fight out of retirement, give him some time to build momentum. That's one of the biggest things in MMA, you have to build momentum.
If you're speaking of Fedor now over chronilogically, then yeah I can see your point.. but to argue that he has only had one fight out of retirement. He's just shaking some rust off, once he builds some momentum he'll get back on track.. especially if he goes to the UFC.
But if you're going to compare Fedor to Brock, most certainly they were no different in their prime. Brock was fighting guys he wasn't ready for and was luckily winning. Fedor fought the best of the best in Pride; Nogueira, Cro Cop, Goodridge, Herring. Then he went to Affliction and beat the likes of Tim Sylvia and Arlovski. From 01-09 he was top of the world. Maybe he won't be at the top, but I certainly won't rule it out.
Given Brock would have had the proper introduction and build up into the UFC, well then yeah, he would have surpassed Fedor. But Fedor has certainly made a history of beating the best in his time!
More importantly though, I'm glad we're in an era where we see hard working persistance paid off. RDA got KO'd in his first UFC fight, now he's the champ. Werdum got KO'd by Dos Santos in 08, now he's the champ. Robbie Lawler was most known for getting KO'd by Diaz, now he's the champ. It's cool that we're having fighters who lack marketing finally getting on top, and it most certainly may be dissappointing to odds makers, but always interesting from an analytic point of view.