I think we should be completely beyond seeing Xhaka, Ramsey and Ozil as a midfield trio unless less they show us something very firm in the way of why we should play that trio.
I think with instruction Ramsey can have the sort of game he had in his standout season. My worry is that Emery hasn't had the time to get into the focus on individuals and has emphasised focus on to the system (High press and fitness) which I wouldn't necessarily criticise.
With that in mind (and admittedly going mostly on reports, world cup cameos aside) I'd say Torreira is the first name on the sheet in midfield. Pair him alongside AMN or Ramsey, then I think you can play Ozil ahead. The discipline of Torreira will also allow Ramsey and Ozil to swap when Ozil what's to come deeper to affect the game from there.
If Guendouzi proves he is ready he seems like a far more mobile version of Xhaka, so I'm increasingly seeing less where Xhaka fits in and why he should play.
I think a lot of what we do actually hinges on a pacey wide player, of which we still don't have!....which is partly why there is such temptation to play Aubameyang wide as well as central. I think if we don't make that signing, it will hinder us sooner rather than later.
Getting rid of Alexi and Walcott and replacing him with Miki was not good for the squad in terms of balance or goals.