CORRECTION: 5/19/14, 2:55 p.m. EDT. A previous version of this story misidentified Ray Senkowski as a former Wiley Rein partner. He is the son of a partner at the firm. We regret the error.

Major League Soccer took a big step in its quest to reach the upper echelon of professional sports this week, tapping Proskauer Rose to advise on an eight-year, $720 million media rights deal with ESPN, FOX and Univision.