Generally, I actually thought Silva was pretty outstanding last year, but got let down by the other players. Without Aguero and Mario for most of the year, he really didn't have anyone to play through balls to, only Zaba and occasionally Milner were making runs in behind. He needs runners, now we've got them in Jovetic and Navas and I expect him to devestate.
Personally, I don't think it matters where you position him on a teamsheet, he plays a free role anyway really. He drifts all over the place, coming deep and going out ot both wings, I think it's far more about who he has to link with