The Alternate Major Leagues are any top professional sports leagues that is not one of the four Big Sports (Baseball, Hockey, Football, and Basketball).
These leagues may attract the best players of that sport worldwide but are small in their scope and marketing because they do not have the fanbase to fund those plans. Even when there is scope and growing fanbase, the league may still be small when compared to leagues played in other parts of the world. Major League Soccer is not considered to be a Major Sports League because it does not attract the best players worldwide despite its success in those other areas.