Germany is probably the world leader in youth production at the moment, although Belgium, Spain and Brazil aren't too far off. We can get Belgians and Brazilians and perhaps Spaniards, but Germans generally tend to prefer to stay in their own country- for them, no club is bigger than Dortmund or Bayern or whatever. And they're right, in a way. Many Bundesliga clubs can offer competitive wages vs. England and Spain, so there's no incentive at all for them to go overseas, is there?