Coaching and training is different. Not the same as culture and traditions, so that makes more sense.
But, as I said, 20 years. It's not like we just discovered soccer yesterday.
And I'll add, the "history" and "traditions" of little league, junior high school, high school and regional all go out the window the minute a new coach is brought in. There's just not a lot of there there to have it weigh so heavily.
The reason Americans are good at sports is because we have a competitive and militaristic society. You're not going to find many places on Earth where more is spent on sport than the US. At the end of the day, that's what wins.