we don't need a CB.
Piqué and Mascherano are established as starters there, and Piqué won't have another injury-riddled season like this one as long as Del Bosque treats him fairly. Puyol is around too and can play at a starter level. Muniesa is coming through and has potential there, Busquets can play there in a pinch too, and I think Bartra is going to surprise a lot of people next season with his CB play.
if we can get someone to lock down the LB spot (Alba or Bale, tbh, but it won't be injury-prone Adriano) then we're covered at the back. spending big on a CB just shits all over Bartra & Muniesa and forces Mascherano back into midfield where he's not as good for us. yes if Puyol retires we'd need a CB, but he's not retiring so we don't need a CB, we need a LB.
and the reason I prefer Bale is because he has the size and strength to be able to play LCB in a back three. I'm sure Alba could play it too, as Adriano has at times this season, but surely not in every situation like Abidal was able to (maybe he can tho? I mean Mascherano makes it look easy). it would reduce the tactical flexibility of the first team because if we wanna play/switch to a back 3 we'd have to pick more of an obvious CB, and then it's harder to switch between 3 and 4 man defences mid-game, or take a risk with Alba in a back 3.
this is all moot if Muniesa hulks out over the summer, because he has all the tools to claim Abidal's LB/LCB spot, but he's not ready to start regularly just yet and I'm sceptical if he will ever make the grade as a starter on account of him having Sadbrows. hope I'm wrong though.