Right now, nothing, because there's not much you can do. Obviously Castillo isn't even a consideration; he's not even hitting well in Pawtucket (Last I looked he was hitting under .250 and slugging around .320). Once Holt gets back, you go back to the platoon. Until then ...
I found it very telling on how far Castillo has fallen in the pecking order when they used Rutledge to ph last night instead of Rusney. He is definitely deep in the doghouse.