Agreed on Polanco, Arraez and Refsnyder. At this point in the season, it probably makes a lot of sense to try to see how the position player pieces fit in the puzzle as much as possible. Injuries will still play into that, but there are some things they can still sort out. To that end, it probably makes some sense to sit Simmons, shift Polanco back to SS for now, and showcase Arraez at 2B. It'll get harder to evaluate Refsnyder once (if?) Buxton comes back and Larnach is still on the roster.
If Donaldson can't get his hamstring to quit barking, then they should IL him and bring up Miranda or play Arraez there.