On the CB front, I really can't see Arsenal signing a big name CB or rather a good experienced CB. There are pretty much about 5 CBs on the books now, obviously if you count Chambers and Holding. With Mertesacker injured for a while it's chance for one of Gabriel, Chambers or Holding to seize the opportunity. For the latter 2, if you're good enough you're old enough.
All it takes is a run of games for either of these players.
All it takes is a run of games for either of these players.