As much as there are issues with the subs seeming like for like, I think that is when a change of shape/numbers to address an issue is just as important if you lack the diversity on the bench.
I know that having the likes of Saka / AMN / Willian drifting infield from the flanks has worked in providing better numbers and options in midfield, the core issue still remains with playing a deep double pivot. It also leaves the flanks exposed on a quick counter when the likes of Tierney and Bellerin as also forward.
IMO we may need to go back a step from Arteta's multi-functional roles, and settle on a basic shape and roles to get the fundamentals in place much like playing to your spine. I'd be tempted to go with a 433 for games we are expected to dominate, and a 4141 for those we are expected to be dominated. Alternatively a 4231 and 4411 respectively. In both examples the only change is the positioning of the advanced wide players. ATM I see little point in having players who have pace if we do not look to use it.