Suggestions for improving my rotisserie fantasy baseball team?

You can definitly get a lot for the players on your bench. If Piazza is eligable at catcher he should be starting. If you were willing to trade Wright you could get a good a Manny Ramierez who is off to a slow start but should pick it up. I would not try to get Pierre because he does not help you with anything other than stolen bases. Try and pick up Chone Figgins who is on the DL but should come off soon; he is an excellent basestealer. Also your pithing is really good if you were willing to trade Santana you could get two players in return. Maybe a Bobby Abreu (although you seem to be a sox fan) and a player like Jason Bay