Armstrong allowed two runs on a hit and a walk and struck out one in one-third of an inning in Monday's 7-0 loss to the Yankees.
Armstrong was called on to finish the fifth inning, but he ended up giving up a grand slam to Giancarlo Stanton before striking out Gleyber Torres. The 30-year-old Armstrong was away from the Orioles at the start of the season to attend the birth of his child. The right-hander is expected to join Cesar Valdez and Tanner Scott in a closer committee to begin 2021, but Armstrong will need to show better than he did Monday to be trusted with a late-inning role.