I would not put Grullon, Haseley, and Moniak on any sort of hard to trade list. Scouts are not sold on Grullon and the criticisms have been more defensive of late. And with Haseley and Moniak, they mainly play the same position and since neither is seen as likely to be an above average regular, one has to think that trading one of them is easy.
I could also see them trading either Medina or Howard (more likely Medina) as a way to include a high-ceiling but risky player in a high end deal. Most teams will want Morales too as much as those other two guys even though he is pretty far away and even riskier.
I think they need to have a shot at the division though to justify trading top prospects and I just don't see that now. Wild card is more of a "tweak but not reinvent" strategy of smaller band-aid deals largely picking up salary. Like a Cashner deal would have been.