The linked post names Bronson Arroyo and Aaron Harang as the usual suspects, but also Brandon Phillips and even speculates that the club might be willing to trade Joey Votto if the acquiring team would also take on a big contract, as they have Yonder Alonso pushing the upper levels of their minor league system. Phillips is very interesting if the Mets are able to move Castillo, as he's essentially what Orlando Hudson was when he was actually good at defense, and with more raw power as well, though this is offset a bit by a lower walk rate. And obviously, Votto would be an excellent buy if that were at all possible. Maybe the Mets could work something out where they deal Murphy and a couple of the better prospects in the system for Votto and one of the pitchers, taking on the entire salary. Ike Davis would have to move to the outfield, but who cares at that point?