But if our best athletes trained for soccer starting at age 4 or age 5......
What's happening is that our 6th best athletes trained for soccer. Athlete = not just raw speed/power but spatial awareness, dexterity, endurance etc.
Plus - American kids don't play soccer for fun. Only time you see them play is when it's a match for some league or travel team. Kids in Africa, Europe, South America etc., play soccer the way brehs go to the LA Fitness gym to hoop. Skill or athleticism? Neither matters because soccer isn't ingrained into our culture.