As has been previously noted, Herrera has the second-highest OPS on the team, and it's only gonna be higher after tonight. What if they trade Rhys (for a closer?), pick up a veteran OF (preferably high OBP or good defense or both) and let that guy, Herrera, Moniak and Vierling share both LF and CF. Put Schwarber at 1B and let Castellanos stay put (and/or DH if Bryce returns to RF). I'm not sure the offense gets any worse and the team just might get better.
Otherwise, send Moniak down so he can play regularly, stick with Odubel and get a RH bat at the deadline if Vierling doesn't re-take the job.