Let me break down the kind of people Fedor was fighting.
http://en.wikipedia.org/wiki/Yuji_Nagata
Here's a professional wrestler that came in, fought fedor and cro crop and left with two losses. Obviously not a can.
http://en.wikipedia.org/wiki/Ryūshi_Yanagisawa
This guy had a history, but by the time he fought Fedor he'd won two of his last eleven fights.
http://en.wikipedia.org/wiki/Chris_Haseman
This guy had been losing to welterweight fighters by the time he fought fedor.
http://en.wikipedia.org/wiki/Kazuyuki_Fujita
This guy lost to every decent fighter he came up against.
Let's be honest here, Fedor's "reign" was a joke. Fedor fought in Japan, and Japan was more interested in a spectacle than an actual competition. If Fedor had been consistently fighting the top guys then that would be one thing, but he wasn't.