The funny thing about this idea: When you look at Messi (5'7/150) or Mbappe (5'10/165), do you see people who are freak natural athletes on the level of Lebron or OBJ? Harry Kane looks like an inbred member of the Royal Family. Yet these are the best soccer players in the world.
Not to minimize their physical gifts, which are substantial. But you can't just take budding NBA players, or even NFL players, and expect them to become elite soccer players. It's a different sport that rewards different skills (and body types). But to your point, the US is a large enough and affluent enough country that at this point in 2026 we should enough world-class soccer players to break into the quarterfinals of the World Cup. Yet we don't. To me, that's a problem more about development than raw talent.
Not to take away from this, but isn't Mbappe one of the fastest players in the entire sport? And in the other direction, Lebron is a freak athlete, but no so much as Wemby or Giannis or even Derrick Rose.
I think the argument needs to not be about how we can take these great athletes from the NBA or NFL and just make them soccer players, but about how those sports have a greater emphasis on athleticism than soccer, so our most athletic players trend to those sports before they can develop the necessary skills for soccer.
We can still develop talented soccer players, but you are going to get fewer great athletes, which will put more stress on the technical skills side, and these players will develop in an ecosystem that does not have the same speed of play as their counterparts in more soccer focused countries.
This could also kinda explain why we have stagnated in World Cup results despite having "better" players. We have players in top leagues in the world, so we feel like we no longer need to play the bunker and counter style of less talented nations. However, the whole team is not at that level, so when we try to a normal game against a good team, our weak links are exposed. But we also cannot play that bunker and counter style anymore because most of our good players are not used to playing that way. So we're kind of stuck between a rock and a hard place.