you seem to be arguing that people are born as sprinters or distance runners and you cannot train one to succeed at the other, therefore you cannot take great athletes from America's primary sports and wish that their innate abilities had been developed for soccer instead of their current sport.
I think you oversimplify, a more comprehensive view is:
1. there are athletes that possess various combinations of fast-twitch and slow-twitch, that alone is not determinate of whether they will succeed at any specific sport
2. physiology tells us that training exclusively slow twitch or fast twitch has a significant effect and can cannibalize muscle ability, there needs to be a balance
3. soccer is not a 90 minute distance run, where the winner is awarded a prize based on distance travelled, I do not agree that most games are decided late in the game when players are tired, Premier league players top out at about 12km run per 90 minute game. Not exactly a blistering distance to cover in 90 minutes. The distances come at a walk, a jog, and at certain positions 50-70 sprints of varying distance. It can get brutal when they play 3 games in 6 days, but they do call up reserves etc. There is a halftime and other stoppages in play.
4. the ability to change direction at speed, to accelerate, and to decelerate are a prerequisite to the value of any endurance in soccer
5. technical ability is also a prerequisite, I agree there is no way to tell whether a Wes Welker who at 5'8" with cutting speed and good hands would ever have developed a touch with good feet. (Pace by the way is not the same as speed in soccer, it refers to different speeds of the player with the ball and without, it is the ability to change pace that is referred to)
6. for the last ten years of his career, (and maybe the first) Maradona could not run 3 miles straight if you put a gun to his head, but he was still great
there are different athletic types playing successfully in Premier League
Sorry if this comes across as a lecture, not meant to be. Everyone can see things differently, I am just trying to clarify why I am saying there are great athletes in the US that it would be intriguing to see train, develop, and perform exclusively in soccer instead of the US $ sports.
One other thing that has been detrimental to US athlete development is that there is a tremendous bias against US athletes going overseas, they typically disappoint at the next level, get less time to train though it, and sent home then not resigned. Worse they get welcomed into the endearing arms of MLS where the comfort zone is good and they can be a success in a small pond.
There is no strategy or reliance on games being decided by late game endurance and mistakes, actual gameplay bears this out:
take the 14' WC round of quarterfinals when teams presumably are better matched and in elimination games:
France Germany Germany scores at 13' game over
Brazil Columbia - Brazil scores 7' in game over
Argentina v. Belgium - Argentina scores 8' in game over
Netherlands v. Costa Rica - scoreless goes to PKs
In the Semis:
Germany 7- brazil 1
Netherlands Argentina scoreless goes to PKs
Final:
scoreless until Germany scores in 118' on a seven player possession combination
And Rojo if it is all about luck, the US is due some
I am going on too much. To each his own. I think we all agree there is room for improvement in US soccer and hope for it. Pulisic will be interesting to watch.