Who to drop for SP chris naverson?

I wouldn't pick him up. Of course his numbers look excellent so far this year, but do a little research before you crown him as an ace. Last year he pitched 167.2 innings and ended the year with a 4.99 ERA. He did have 130-something K's in that many innings which is pretty good, but the pitchers that you have will be better than him after he cools off. If you want to gamble and pick him up anyway I would drop Soriano, because I don't think he has great value unless Rivera gets injured.