No one uses 4-2-3-1 any more, seems to me Arteta is using a dated formation that basically is trying to copy Wenger but with more defensive players rather than creative.
Not great for me, almost every team in the top 4 in every major european footballing nation uses either 3-4-3 or 4-3-3 but I'm assuming Arteta is going to persist with his formation unfortunately, it also means we need a very specific type of striker.