Yes I understand that, but every US kid with any potential finds his way to the u17 residency program, which is like Clairfontaine I guess. In theory they should get the best coaches in the country there. But in a nation of 300 million, we can't even produce as much talent as the city of Porto. Don't even mention Lisbon.
I don't believe in this stupid fantasy that worldclass players just become crap in the spsce of a year or two, much less players who relied on intelligence and creativitt and technique. It doesn't go away, it is more likely off- field or fit issues.