As a short term signing while Baynes is injured, as short term added depth options, how about:
(a) Tyler Zeller
(b) Brandan Wright
(c) Willie Reed
Current free agents who can provide some depth behind Theis and Williams.
I like Reed the best. A big body. Something different matchup to Theis & Williams and to Zeller and B.Wright who are both lightweight. Reed offers some muscle.