the question is do we need a top-drawer CB?
i think no..
Pique, Puyol, mascherano, abidal(if and when fit) and then we have bartra and fontas..
it is better to go for a LB, considering what to do with adriano also..
Fontas just isn't good enough (slow as shit) and I'm really not sure about Bartra either. I don't know if you've been paying any attention but Puyol hasn't been the same since the injury and he's getting old. Puyol will be good as a rotation CB for a few more years, not a starter sadly. Abidal is getting old too and is about to get a liver transplant...that's a big deal dude, there is no gaurentee that he'll even ever play again.
And Bale is exactly what we don't need. If we brought in Bale or Alba we'd have to offload Adriano, and I think he's been great for us when he hasn't been injured. People don't realize how clutch Abidal has been for us, he's been awesome and cleaned up our messes much like Mascherano is doing now. Most importantly he is tall, has pace and is primarily defensive minded....this allows Dani Alves to do what he does. Bale and Alves on each side is mouth watering but it's not very realistic.
I'd prefer an LB that can play as a CB like Abidal...but I don't think one exists, at least I can't think of any. Maybe Sakho but PSG has way too much cash to ever let him go.
Even if we bought Thiago Silva (drool x 1000), there would still be a huge question mark for LB. Who would be our steel on the left?