The Nationals have reached an agreement with reliever Sean Burnett on a contract extension that will keep the left-handed reliever with the Nationals through the 2012 season with a dual option for 2013, according to a league source. Burnett had a 2.14 ERA in 63 innings over 73 appearances with 62 strikeouts and 20 walks while converting three saves. During the final two months of the season, Burnett allowed three earned runs in 26 1/3 innings.