Thomson always loves to give guys that full two day rest.
This team does not need to play to win every game, even after what we just went through. That includes having a batting practice pitcher as your #5 (now that Suarez is about to be back and, we hope, Sanchez is on the upswing). No point in going all-out for the #1 seed (in NL or MLB) if you you have tired or banged-up players, and possibly not even any point in going all-out for the bye given how that's worked out for the Dodgers and Braves so far.
That's not to say they aren't focused on that, but not to exclusion of all else.
Maybe Dylan Covey can have Walker's spot. I don't think mollifying him or finding a role for him is an issue at that point. If they aren't able to offload his contract he will have to come to spring training to win his job, and face a DFA if he doesn't.
But he still wasn't an outrageously bad signing. He earned his salary last year, and then he got hurt (twice. Yes, the blister was real). At his age he may never improve again and the signing does look dumb given he's easily replaced and then some by the likes of Sanchez and Turnbull. Not to mention Eflin has defied the odds and been both the better and healthier pitcher.