"It wasn't quite as good as we hoped it would be," Showalter said. "It's slow. We said at the time, when you get that high hamstring, especially with his delivery, how he's got to get down on that leg, it's slow. No setback or anything. It just didn't move forward much."
Showalter wasn't sure if this would change O'Day's timetable or not.
"We'll see how tomorrow comes. He may take another side," Showalter said. "He needs to repeat that good side he had the other day before we go into that sim game."
Rehabbers Vance Worley (groin) and catcher Caleb Joseph (testicular injury) both continued their respective assignments for the O's Class A Frederick team. Showalter wouldn't comment on whether Joseph would be an option for the Seattle series that starts Thursday.
Brittany Ghiroli has covered the Orioles for MLB.com since 2010. Read her blog, Britt's Bird Watch, follow her on Facebook and Twitter @britt_ghiroli, and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.