I think he wants a better passer in there than either of those two are and wants a left/right combination. I expect it's currently between McAtee and Schlager to partner Sangare v Leeds. Unlikely to be McAtee at Anfield and may pick Dominguez for his workrate.
Seems like he sees Yates as backup central defender, rather than a CM. Cooper tried him there for a bit before he had a disasterous 20 minutes in a home game (in the championship, I think?) and abandoned the experiment.