He only gets in the Brazil team as Marcelo had a big bust up with the coach and refused to apologise and so has been dropped.
Bastos isn't a left back.
However, he can't possibly be any worse than Traoré so at least it's an improvement on what we already had there and will hopefully keep Vermaelen in the centre. Plus at 28 he's got the experience to help Gibbs in his developement.
A good signing, not a great signing.