If Nasri and Fabregas were to leave wot would our midfield be? Mine personally would be (if we made no signings?: Rambo Song Wilshere But knowing Mr Wenger it will most likely be: Diaby Song Wilshere
I would try Arshavin in the number 10 position because that is where he is supposed to be played. But if he still didn't return to form I would do your formation.