I think the 2014 World Cup in particular is a big part of this, yes 2010 was big, but I think 2014 made the sports impact more permanent. Instead, ever since 1994, soccer has slowly and steadily managed to sneak itself into the American sporting mainstream.
Ever since Pele and the Cosmos took America by storm in the mid 1970s, critics and fans alike have predicted that soccer will explode in popularity in America and for decades, and for decades we waited as that prediction failed to materialize.