What about Mathieu? He was a left winger that has been transitioning well to cb. And their defense isn't poor, its built well to suit their style of play. If their style of play was to constantly defend from the cross and long balls and to try and constantly defend and counter then yes its poor, but it is not designed that way. So saying they are poor center backs just isnt true. And Cesc came through the barca academy in the xavi position, so him not knowing how to play that position isnt true. There was no space to use him in the center for both club and country at barca and his best chance to play and get playing time was to play striker which any player would do instead of waiting for 3/4 years for xavi to finally leave and maybe take over for him. If he only had to wait for a year or two then the transition into the center mid would have been easier for him. The attacking position he played in england would easily transition for him into barca's system since they aren't the pep team of tiki taka anymore and have gone into more direct attacking play which would suit fabregas. But I think they should have at least gone for Koke, verrati, or even perhaps pastore if the other two weren't available. Don't get me wrong I hope Arda turan does well at barca since I have been a fan since 2008 euro's and his days at galatasaray, I just don't see his style of play or most of atletico's players fitting into a barca system