Yes, ERod is a "nibbler," but he has some of the nastiest stuff on the staff. He's also improved on his IP'd, slightly. Trading ERod only makes sense, if we are looking for a 2-3 year rebuild, not the one year plan I'm thinking might be possible (reset in 2020).
I love Workman, but he's a FA after 2021. He has trade value, too. If we plan to be highly competitive by 2021, he'll have 1 year in the next window.
Barnes has seen his stock fall. I'd keep him, in hopes he improves and can help in 2021 or be traded next July.
Hembree's stock is low, too. I keep thinking we'll see his upside, and maybe we started to this year, but who knows. I would not trade him for scars, unless it puts us under the tax line.