As long I can remeber Santon is a RB and not a LB, but he is a great choice, he is doing wonders at my Arsenal (yap, Sagna is a 2nd choice, don't cry). You just have to give him time to evolve.Mathieu and Maicon are great prem quality full backs. If you want to get some great future stars in at RB and LB, try Santon for LB and Rafael or Jordan Spence for RB.