He won the Strikeforce GP without ever fighting the best HW's: Werdum & Overeem.
He has good wins, but realistically only 1-2 elite wins.
As for a prime vs. prime fight vs. Fedor, his best bet would be a LnP decision win, but he's too sloppy on the ground as he leaves himself opened for subs. Catching Fedor on the feet was hard. He could land a bomb, but chances are he wouldn't (Fedor stood with guys like Crocop, Arlovski, Hunt). Cormier's poor striking defense wouldn't help him either.
Fedor simply had a lot more tools at his disposal and was a far less flawed fighter,.