#3 Imbalanced midfield full of gaps
Arsenal's defenders may have borne the brunt of their team's catastrophic run of form in recent years but the midfielders are equally to blame for their vulnerability.
Since the start of the previous season, the Gunners have made more individual errors leading to opposition shots than any other team in that period, with Granit Xhaka and Matteo Guendouzi among the players who are most prone to such mistakes.
Having worked with highly-rated defensive midfielders at the Etihad, Arteta may take some time getting used to error-prone players like Xhaka, who lack pace and movement on the pitch, and will have to sharpen young players like Lucas Torreira and Guendouzi by recommunicating the importance of discipline, tactical positioning, and defensive support during counter-attacks.
Dani Ceballos, on the other hand, may offer plenty of creativity and control in the final third but he is certainly not inclined to the defensive facets of the game.
This leaves Arteta with the task of bringing positional organisation and structure to an incredibly imbalanced midfield, a change that would be crucial to his attempts of rebuilding a more compact team.