Really? Did we not just beat Manchester City. Were the midfield not competing? Did we not beat Barcelona last year at home, were they not competing then? How can you say that the mdfield can't compete, when they just proved that they can compete? They didn't just compete, they dominated.
1. New players need to adapt to playing for Arsenal, and old players need to adapt to the new system. 2. A shedload of defensive injuries forcing us to rely on youth like Miguel and Jenkinson. 3. Relying on Ramsey in attacking midfield (no Rosicky and no Wilshere). 4. Relying on Gervinho on the left. The big transition is over; the defensive injuries were very unlucky but we can buy Vert to have more quality in depth; Ramsey is no longer a starter (although he's out there playing rubbish against Wolves right now...); Rosicky is flying, Wilshere will be back, and we'll have Podolski over Gervinho. If you want to buy one more central midfielder then make a case to drop 2/4 of these players: Arteta, Song, Rosicky, and Wilshere, because one is going to be dropped as it is.