Exceptions exist, obviously, but ronaldo is only 6’2. Zlatan is 6’5 and he is extremely tall for a soccer player.
Serbia has the tallest team at this World Cup at an average of just under 6’1.
Argentina and Spain both average 5’10.
I’m not saying there are no tall soccer players, but there just aren’t that many tall people who also have good enough feet to be great soccer players. Being tall is a great advantage when attacking balls in the air, but you simply don’t see teams trotting out guys at 6’6+, especially outside of GK and CB. From the NBA, that pretty much leaves you with small guards.
There is, I think, something to what you’re saying. But I think where US soccer really loses is with undersized basketball players and defensive backs, slot guys, scat backs, that type of athlete who plays fb/bb until/through high school and then they’re too undersized/don’t have enough straight line speed to hack it at a higher level. Those guys have prototypical soccer bodies, particularly if they don’t put on the weight required by football. But by the time they realize they’ll never be D1 football players, it’s way too late to develop soccer skills to an internationally competitive level.
Despite all that, there are plenty of athletes to go around for all the sports, and plenty of kids playing soccer to feed the national team. We need better coaches and better development, and to find a way to break away from the pay for play youth team model that drives clubs to focus on winning (so they can recruit more kids and their parents’ money) rather than developing players. The college model doesn’t help either, because players at that age in other countries are being integrated into professional teams and practicing with professional, grown men every day, while guys here are in class.