In terms of activation from the disabled list, which O'Day was eligible for Wednesday and which manager Buck Showalter thought at the time of the injury would be something that happened quickly once the rules allowed, Showalter said there's "nothing imminent."
"He's getting a little better every day," Showalter said. "It's really slow moving, but he'll get there eventually. We're getting close to the time where he might have to go out on rehab, but it's been a long [one].
"This has gone a little longer than we thought."
O'Day was placed on the disabled list retroactive to May 6 after he said he hit his arm on another person while throwing in the bullpen, which is a hazard for someone who throws from the low angle he does.
Showalter said there's "nothing structurally" wrong, and an MRI revealed as much shortly after the injury occurred, but there's one bit of soreness that they're trying to manage.
"He had a pretty [good] kind of hyperextension there, and it's going to proceed at its own rate," Showalter said. "I'm not going to make him. ... Darren knows his elbow real well. We're just not comfortable pushing any faster than he's pushing it."
When O'Day first went on the disabled list, Showalter didn't believe he'd need a rehab assignment, as it wouldn't be too long since he appeared in a game. Even if he's able to return this series, it would be almost three weeks off since he last pitched May 4.
"It's a challenge," Showalter said. "It's going to move real fast once that last little bit gets out. Then, it's just a matter of whether he's going to go pitch in a game that night or go pitch somewhere else. It's close. It moves at its own pace."
Tillman schedule made
A sheet of paper was added Monday to Showalter's pile of rehab schedules, as right-hander Chris Tillman's first time playing long toss since he landed on the disabled list with a lower back strain on May 11 allowed the team to plot out his path forward.
"First time he had a ball in his hand, and it went well," Showalter said. "After that happened, [head athletic trainer Brian Ebel] got the schedule for him. They've kind of scheduled him out. I just got the calendar, so now he'll start proceeding to the mound."
Tillman left the team last week to report to Sarasota, Fla., for his rehab. His injury came at a time when he was sure to lose his rotation spot, with a 10.46 ERA in seven starts.
Hess sticks around
Right-hander David Hess stayed with the major league club after he made his second big league start Sunday, and Showalter said he'd remain in the rotation for the next time that spot comes up on Friday.
That doesn't mean the team doesn't still want to see Miguel Castro start, as was the plan before last Tuesday's postponement.
"I really want to see Miguel start," Showalter said. "I think we all do, but unfortunately, he's so valuable down there. We probably would have still brought David and had him behind him, but right now, I'm planning on David starting [Friday]. But, if we get there and for some reason, Miguel doesn't pitch for four days, I might pitch them together. But the chances of him not pitching the next four days is pretty challenging."
Another simulated game for Britton
Closer Zach Britton (Achilles) will throw a one-inning simulated game Tuesday before ramping up to two innings Saturday when the Orioles travel to Tampa Bay, the last two steps in his rehab before he goes on a minor league assignment.
Showalter said he'd report to Triple-A Norfolk on May 30 if those two outings go well. Britton and Showalter have both said they hoped to get most of his work done in controlled settings with the major league team versus making many minor league appearances, as he did last year on his way back from a forearm strain.
Around the horn
Center fielder Adam Jones, who left Sunday's game with illness, was better Monday, Showalter said. "He had a certain green-ness to him," Showalter said. "When he came off the field in the first inning, I watched and I knew something wasn't quite right. With each hit he got, he said, 'Man, I'm not trying to do too much. I'm just flipping it into right field.' I wanted to go, 'Maybe you found something here.' But that's the thing with Adam. That's why I appreciate and respect him so much." ... Infielder Engelb Vielma, who suffered a fractured kneecap at Triple-A Norfolk earlier this month, is having surgery Tuesday, Showalter said.