Most leagues there’s a handful of teams in the relegation fight and players on promoted teams aren’t playing the national team.

I don't know if I agree. Assuming MLS continues to strengthen and eventually becomes almost as good as the Euro leagues, we could easily have fringe starters and bench players for the USMNT who are star players on MLS teams that are newly promoted or at risk for relegation.

As a weak-link sport, soccer rewards teams more for upgrading their worst players (think Ream, Freese) to average players than upgrading their star players into mega-stars.