I still haven't heard anything on Downs, but Jordan Bastian has tweeted that Casey Janssen is going on the DL with right shoulder inflammation and that Brad Mills will be called up to take his place and pitch on Thursday afternoon.

This likely has more to do with the short notice and whose turn it is than Mills' performance for Las Vegas.  Mills is 1-8, with a 4.48 ERA and a 65/35 K/BB ratio over 76 1/3 innings.  He has given up 5 or more earned runs in 3 of his last 4 starts, though he did have a stellar outing two starts ago in which he struck out 11 and walked no one over 7 shutout innings. 

As for Janssen, the evidence continues to mount that he is not sufficiently healed from his shoulder problems.  Here's hoping he gets some rest and feels better soon.  Originally, Ken Rosenthal had reported that Mills was set to pitch with Janssen moving to the bullpen, but Bastian says it's the DL for him, which makes more sense to me, though moving Janssen to the pen could make sense if Downs is expected to be out for a while.  More as we hear it.