MacDougal, an All-Star for Kansas City in 2003, had 20 saves in 21 chances last season and went 1-1 with a 3.60 ERA. He was released by the Chicago White Sox on April 29 with a 12.46 ERA through five appearances and signed by the Nationals on May 3. Chicago remained responsible for most of his $2.65 million salary.
MacDougal has 70 saves in eight major league seasons.
Olsen was 2-4 with a 6.03 in 11 starts this year, his first after Washington acquired him from Florida. He did not pitch after July 10 and had surgery to repair a small tear in his left shoulder.