The released reliever after the right-hander gave up three runs in less than an inning of work in a second consecutive appearance.
Sims, who turned 31 on Saturday, had a 13.86 ERA in 18 relief appearances this season.
In parts of nine major league seasons with four teams, including seven seasons with the , Sims is 23-19 with a 4.86 ERA in 263 appearances (14 starts).
In a corresponding move, the Nationals recalled right-hander Zach Brzykcy from Triple-A Rochester.
Brzykcy, 25, has seven career relief appearances over the past two seasons for the Nationals with a 13.50 ERA.
