I think sunk cost is being used incorrectly here. If the alternatives are to dump him (and his salary) for a minor league roster filler vs. keep him on the roster, an argument can be made to just keep him (he's not exactly blocking any 1B prospects right now). This has nothing to do with sunk cost. Terry Ryan can just as easily dump him in August. My take reading between the lines is Terry Ryan didn't just want to dump him, he wanted something worthwhile in return. I think the lack of any return, not the money, was the more decisive factor.