Neither of those guys makes any sense to not have signed. Keuchel has made $32 million, Kimbrel has made $55 million. So even on a one-year deal you gotta think Keuchel would be making well over half his career earnings, and Kimbrel would probably make a third of his.
I understand how a guy who's made $200 million might not come back for a couple million extra, but I do not understand how you turn down $15-20 million pillow deals if you're one of these guys.