I don't see why not. Clearly here in Britain we are limited by the 90 minute rule (although not sure how that works considering we signed the likes of Agard from Arsenal) but our academy has a number of youngsters from overseas, and Moyes has signed a good few this summer alone. I don't think we should give up and say that Barca are so good because of who they are. What they do and the way they do it clearly plays a huge part, and there's no reason why we can't replicate that.
The difference is cultural. I dare say the likes of Xavi, Iniesta and Messi would not have come through the British system because they're too small. Even now we get people on here poo poo-ing Kissock purely because of his size. This is driven largely by the competitive nature of youth football, with results seemingly more important than education. Concentrate on the process and the results will come in the end. Concentrate on results first though and you'll fill the youth teams with bigger players with less technical ability simply because they're the youngsters who get results in youth football.
