I completely agree that the midfield is a wreck because each player needs a different system to get the most out of them. There's really no way to get Ramsey, Ozil, and Mkhi all into one team, especially with both of Auba and Lacazette. If the backline was world class then maybe you could force it, but that's certainly not the case here.
I think the most effective lineup we could put out is:
Auba
Mkhi - Ozil - Ramsey
Torreira - ???
Monreal - Kos - Sokratis - Bellerin
Obviously there would still be issues, but that gives Ramsey, Ozil, and Mkhi more freedom and less responsibility further up the pitch. Ramsey has played well as a wide AM before, but we'd run into the problem of congesting the middle and not having enough width. The fullbacks would have to compensate to provide width and we'd be exposed defensively still.
Arsenal desperately needs a true winger, a Cazorla replacement and an upgrade at CB. I still think there will be a chance to make top 4 this year though, as the other top teams outside of City and Liverpool aren't all that much better.