DC United reject De Rosario option
United general manager Dave Kasper says Thursday's move was ''a difficult decision to make.''
De Rosario leaves United after 23 goals and 21 assists in 68 games since arriving from the New York Red Bulls in a June 2011 trade.
In 2012, as captain, he had seven goals and a club-high 12 assists to help United reach the MLS playoffs for the first time since 2007.
This season, De Rosario had three goals and two assists as United went a league-worst 3-24-7.