A dangerous thread to make, I know.
I suspect that Fedor is getting a tad overrated by those in the MMA world. Yes, he probably has the best legacy of any MMA heavyweight, and did manage to defeat both Crocop and Nogueira--the latter repeatedly. I would also be the first to admit that he is one of the most well-rounded fighters in the game today, and his adaptability is a thing of beauty.
However, a few things must be borne in mind. He has been inactive as of late, and has not fought a truly top-tier heavyweight since Crocop. Moreover, we are entering a new era of the heavyweight division, where the best from both the UFC and PRIDE are able to contend against one another. We are on the threshold of seeing a new undisputed
champion of MMA, and Fedor has not yet achieved that distinction--he has dominated what is, in essence, half of the division. The better half, but still half.
Fedor has already clearly established himself as the best MMA heavyweight during the early 2000's era. Arguably the best heavyweight of all time thus far. But if he does not manage to win the unification bout, history may remember him only as the best of the pre-unified champions--a standout fighter during an era of fragmentation, but not "the man" in the same sense that the first undisputed champion will be. To draw a boxing analogy, a bit more like Wladimir Klitschko than Lennox Lewis.
Now feel free to rip me to shreds.