The Nationals optioned Poulin to Triple-A Rochester following Wednesday's 3-2 loss to the Guardians.
For the seventh time this season, Poulin served as an opener for Washington during Wednesday's contest. The lefty struck out a batter and gave up no hits and one walk over a scoreless frame before Miles Mikolas took over in bulk relief. Washington didn't announce a corresponding transaction but will add another player to the active roster as a replacement for Poulin prior to Friday's game against the Padres.