This is exactly the kind of thing you need to do in keeper leagues, especially in deeper leagues. Find an injured player that's gone for the rest of the year, and target those players. Owners, especially if they are in contention are more apt to make a trade.
Jonathan Sanchez won't do it, but perhaps giving him a replacement for Posey as well would do it.
Try Sanchez + Napoli for Posey and maybe a young inconsistent arm. Otherwise maybe post his lineup and we'll see if there's something else there.
Keeper League:
F) N.Backstrom, E.Malkin, V.Lecavalier, P.Mueller, A.Mcdonald, B.Boyes, A.Hemsky, S.Horcoff, K.Turris, D.Jeffrey, M.Perreault, C.O'Reilly, S.Upshall, M.Erat, S.Gagne, D.Legwand D) S.Souray, M.Streit, A.Babchuk, T.Gilbert, I.Cole, J.Hillen, M.Methot G) B.Elliott, S.Varlamov, C.Ward, J.Reimer P) N.Kadri, E.Kuznetsov, S.Shirokov, V.Tarasenko, J.Blum, OEL, J.Moore, O.Pavelec