Defensive Midfielder
We know how smooth and tactically strong Wenger wants his team to be. So typically, an Arteta and a Cazorla fit the bill. But when it comes to choosing a defensive midfielder, a lot of emphasis has to be laid on the physicality of the enforcer. Arsenal were never able to replicate Viera and Gilberto Silva, mostly because their successors were never able to take down a rampaging opponent. Victor Wanyama springs to mind, but Diaby was a similar choice and he eventually fizzled out, with the occasional spark.
The numerous midfielders that form the midfield can easily be categorized as attacking, and that makes for a top heavy squad. If the defence really has to cut runs short, a dependable enforcer is imperative this season, and should probably be on the top of the summer shopping list.