There was no need for Gonzaga fight, should have fought Couture straight after Sanchez. He had higher reputation in MMA world at that time than UFC champion, should have not accepted anyone less than Couture at that time, or title fight vs Sylvia instead of Couture. All other fights were high risk low revard. Gonzaga was nobody then, just risk.
Cage and unified rules changed everything, helped his opponents with large space, circling, distance, no corners, and long fence pushing.
In the ring and Pride rules Cro Cop could run throught Miocic, Jones, Cormier or whoever from UFC, he would have at least even chances to beat anyone of them in the ring.
They are all dependant on american version of MMA for their game, Jones needs elbows and big space to move and keep distance and reach advantage, Stipe needs big space, fence and elbows, Cormier needs wire fence, elbows and rules that protect and favour wrestlers. They would all be weaker in the ring, and Cro Cop is a lot better in the ring.