Stevenson is left-handed so they could play him with Marsh. Not sure who would play CF in that lineup though I also think Rojas will get the majority of time.
On the pitching side they probably want to look at Lazar before the winter and the deception in his delivery might be effective the first time around. He did start to get hit in the last few weeks so this might be a short stay until Walker is back though I suppose anyone with options could be sent down. This lines up with Walker starting Tuesday and the team not wanting to be shorthanded before that.
Hall and Castillo were not getting called up this year so they'll be free agents in the offseason. Hall seems a pretty good fit for Japan or Korea if he wants to prove he can hit consistently.