OP here. Good thoughts. Certainly the system itself plays an enormous part in development. I guess the analog here in the US is comparable (though not identical or as immersive) as the European model for soccer is year-round training for football. Many players in FL for instance play nearly year-round honing their skills from age 10 onward. So, a system like that for soccer would surely increase our nation's potential.
I agree also that population alone is not a deciding factor. But my larger point is that there are a lot of incredible athletes in the US; it's just that most choose not to dedicate their time and energy from a young age to develop those skills specifically for soccer.
As for all football players being 'fat' or basketball players being 'gangly' or whatever, I think a PP nailed it pointing out that there are specific positions within those sports that are specialties (linemen in football, centers in basketball) that feature skill-sets not translatable to soccer but other positions that would translate nicely I would guess.
Hell, as a great example, football punters flop in similar fashion to soccer players when any degree of collision occurs to draw penalties
