Pride and UFC are completely different fighting arenas with different requirements. Silvia does have some take down and submissions. I just watched the Fedor/Cro Cop fight on Youtube and it looked like K1 on steroids (maybe was, considering no testing policy). Very few take down and a LOT of wild KO type punches. If Silvia can turtle up, limit the number of thigh shots he takes and uses his reach and ground work, he has a chance.
Silvia is a gangly, ugly fighter, who fights to his strengths.
People may hate that, but you better respect it. He avenged his loss to AA and I have not seen anyone else beat him in a while.