Washington Nationals first baseman Adam LaRoche and relief pitcher Sean Burnett each declined their mutual contract option for the 2013 season on Thursday, making both free agents.

LaRoche turned down a $10 million salary for next season, with Burnett opting out of a $3.5 million option.

Both players were key contributors to Washington's MLB-best 98-64 record and unexpected run to the National League East title in 2012.

LaRoche delivered a career season, establishing a personal best with 33 home runs and recording his second 100-RBI campaign while batting .271 in 154 games. The soon-to-be 33-year-old also earned his first-ever Gold Glove Award this past week.

In nine major league seasons, LaRoche has amassed 197 homers and 684 RBI along with a .268 average with Atlanta, Pittsburgh, Boston, Arizona and Washington.

Burnett is regarded as one of the league's better lefty specialists and held southpaws to a .211 average in 2012. The 30-year-old also posted a 1-2 record and a 2.38 earned run average with two saves over 70 appearances.

Since joining Washington midway through the 2009 season, Burnett has registered a 2.38 ERA and saved nine games over 245 games pitched.