Both Silva and Jackson fought for other org's for well over a year before joining the UFC ( Orgs which utalize the cage funny enough), so they didnt come direct from Pride, Nog has done well although he has an intrim belt and one of his two wins comes from an ex pride fighter.
look at the bigger picture Prides biggest stars have all had bad luck in the UFC or at least have not performed to the level expected off the top of my head
Wanderlei- Didn't perform poorly. He put on a war with one of the best strikers in the sport. Shogun- Legitimately sucked Cro Cop- give you this one too. Dan henderson- Only lost to two other people who competed in pride, and did a HELL of a lot better against silva than the UFC MW champ did, and WAAAAAAY better against rampage than chuck did. Ryo Chonan- was a middling guy to begin with Rameau Thierry Sokoudjou- got beat by someone who primarily fought in rings......in japan and brazil. Fabricio Werdum- Is in line for a title shot. He's doing just fine.