O'Day was placed on the DL for a right shoulder strain on June 7. After he throws, head athletic trainer Rich Bancells will plan the next step in the righty's rehab.
"I'm not sure [what his next step will be]," Baltimore manager Buck Showalter said. "Because he's been down this road a few times, we're gonna kind of lean on him. He knows when he's ready and when he's not and what's right and what won't play up here."
O'Day had been pitching well for the Orioles prior to the injury, only allowing three earned runs since his outing in New York on April 30. During that span, O'Day lowered his season ERA from 6.10 to 3.86.
Since O'Day was placed on the DL, the Orioles have gone 3-8, and losing him after closer Zach Britton went on the DL at the beginning of May has hurt the team's bullpen.
"It'd be nice to get [O'Day] and Zach back," Showalter said. "[We] have had a lot of situations that we were not able to stem the tide, so to speak."
Depending on how Monday's pitching session goes, O'Day's rehab assignment could be brief.
"I hope [the rehab assignment is short], yeah," O'Day said. "I want to get back."
Until then, the righty chooses to watch the games from the bullpen rather than the dugout because he thinks it allows him to stay in the flow of the game even if he's not pitching.
"[Britton] likes to sit in the dugout" O'Day said. "I've been sitting in the 'pen. We actually talked about this the other day. If you sit in the 'pen, toward the end of your rehab, you kind of make sure you get a feel for the game. Kind of stay in the flow of how it goes down there, and I think it's helpful. So I think he's going to join me down there in the bullpen soon."
Mandy Bell is a reporter for MLB.com based in Baltimore.