One thing that improved under Arteta is positioning and discipline. Players clearly know what is expected of them and throughout the game it is easy to see what their instructions were. However it seems that we are too rigid at times, which was easy to see in today's game.
Every time we moved the ball from the back the only player showing for a pass whenever Ceballos or back four was on the ball was Xhaka and he was only returning the pass. Ozil stayed very close to Pepe and it was harming us in two ways, firstly we couldn't move the ball forward often and/or quick enough, secondly Ozil and Pepe have zero understanding with each other.
While I think Arteta did it to improve our general play on the right wing, it clearly didn't work at any time and he wasn't willing to change shape or give players different instructions, this lack of flexibility is most likely going to be a problem against better teams and in games in which we concede first. Generally speaking, his late subs and stubbornness are two things I am slightly disappointed with so far.