Trumbo, slated to get an MRI on Tuesday morning, has a right rib cage strain, and the team chose to err on the cautious side. He suffered the injury, initially ruled a tweaked back, in the weight room in Texas on Sunday morning.
Given the team's roster crunch (they had to add Hellickson on Monday), the O's couldn't afford to wait on Trumbo any longer. The team's primary designated hitter, Trumbo was replaced in the lineup by Trey Mancini on Sunday, and Mancini started again at DH on Monday. He figures to get the bulk of the playing time in Trumbo's absence.
Coming off a career year in 2016, Trumbo is batting .238 with 17 homers and 50 RBIs in 103 games this season.