Mexes was Burdisso's backup this season.
And yeah in terms of passing, Mexes is decent/technical, but in terms of defending, he is really an example of the brainless defender. Giorgio is a no nonsense defender, as in he doesnt like to have the ball (unless he is randomly counterattacking), and wants to make the safe choice, but defenitely dont think he is brainless in what matters, the defender. Wouldnt say the same with Mexes (when at his worst inconsistent self).
But yeah, either way, if the price is right, sign him.