If you think Castro is a franchise building block (I don't, for some reason some do) then I guess you can spin Lee as being expendable. But Lee is going to be really good pretty soon, around the same time Castro's arb years would be up and well after the time his defense should have moved him off the position anyway.
They probably lost that trade, yeah, but they can still hope to flip Garza this deadline and try to recoup some of that talent loss. This apparent oblique injury shouldn't affect his trade value come July.