Is This a Good Trade?

This is a great trade for you. I wouldnt hesitate one bit. Carlos Santana is have an average season so far and Ike Davis is replacable. Buster Posey is a versatille player who you can play at 1B and C. His stats this year our much better than Santana. This also allows you an open spot where you can pick up a player such as SP Kyle Losch who is pitching lights out or 2B/SS Jed Lowrie or OF Jeff Francour who are all available in majority of leagues out there.