What sort of guy hates Pride and loves the UFC? I've seen people get very attached to fighters, but not fight organizations. Why do you get all hot and bothered over this, did the entire Pride organization sleep with a female relative of yours or something?
Wanderlei was already on the decline by 2005, because he wasn't the same fighter in the MW GP. That was ****ing obvious to anyone with eyes. His toothless performance against Arona just wasn't the Wandy of earlier years.
Look at this way - in Pride, Wanderlei ****ing annihilated Rampage not once but twice. Then by the time they rematched in the UFC, Rampage knocked him cold. Had Rampage suddenly changed from the Rampage of old into Roy Jones? Nope. He was the same fighter he has always been and always will be, Wandy was just a more fragile, downtrodden fighter by then.
Hendo was getting old, his stamina was on the wane, and he started to become too reliant on power punching. He was still a top fighter in the UFC, just not quite as good as in younger days, like 99% of fighters.
IMO, Big Nog definitely wasn't the same fighter in the UFC that he was in his peak in Pride. Again, simply watching his fights is all the evidence you need of that. The wear and tear of fighting Fedor, Barnett, Crocop, Kharitonov, Werdum, Coleman, Sapp, etc, had clearly worn him down a bit by then. By the time he fought Mir he was shot.
The only one I would say who was still the same fighter by the time he hit the UFC was Crocop, but that one massive shocking kick from Gonzaga changed Crocop. It was such a devastating KO, both physically and mentally, that I don't think he's ever been the same. But I wouldn't argue that he was declined before that fight, because he'd looked absolutely superb in the HW GP less than a year before the Gonzaga fight.
Basically, all those guys spent years destroying each other in Pride, and almost all were older and more beaten up by the time they got to the UFC. The only guys who were as good in the UFC as they were in Pride were guys who were very young in Pride (Shogun) and guys who never seen much action in Pride (Anderson). The older mainstays weren't the same forces that they were years earlier, and as I've said, the evidence is on tape for you to check out.