For MLS to grow, it needs to fill stadiums with Joe Sports Fans, the kind of folks who aren't soccer bores but will attend a few games a season.
The MLS needs people who enjoy any sports to fill the stadium. 
mnli hypothesis: The MLS needs people who enjoy any sports to fill the stadium.  premise: For MLS to grow, it needs to fill stadiums with Joe Sports Fans, the kind of folks who aren't soccer bores but will attend a few games a season.