I would argue that American soccer players are great athletes, just not great soccer players. Thats the problem with soccer and greco. It's not that our best athletes don't play those sports, it's that we aren't perfecting the technique. It's not because our greco wrestlers aren't athletic, their just not as skilled. Technique and strategy are very, very important in high level greco wrestling and soccer ball.
Yes, it helps that if everyone plays the sport. But our lack of success isn't because our athletes horrible. They're just not as a skilled or seasoned imo.