No offense to Luiz (he's awesome), but would they not go for someone who's a bit more, erm, 'reliable' in the defence? This guy is class at some points but at other points I cringe at what he does.
Maybe he'll do okay at Barca though -- it's possible his weak positioning won't be much of a problem there compared to here? Not that we should sell him anyways considering we needed to get a CB this year ffs.