Cahill, Jagielka and Samba are all half decent but I really don't think there's a gulf in class between them and Djourou/Koscielny. I think Wenger would have done better to sign Cahill (or Jagielka, as he so nearly did) last summer instead of Squillaci but ultimately none of those players are a cert to occupy the spot next to Vermaelen.
I'd possibly look to bring in a better left back, maybe Baines? But aside from that we'd benefit more from buying a couple of strikers and wingers that have proven themselves at a high level and can make a difference week in, week out rather than focus on the defence. Oh and buy someone to replace Denilson.
