O'Day completed a successful simulated outing before Tuesday's game, and Showalter said he will have another simulated session on Friday.
"We want to see how he responds the day after," Showalter said. "He's not out of the woods, yet, but he's very close, we hope. This is as close as we've gotten in a while. We've gotten a good return on it. I know there's not a whole lot of games left. Just needs to follow a certain protocol physically to make sure there's nothing. … We plan on Darren being with us for a while, and we don't want to do something that's going to rush back and create another problem that could be averted."
O'Day – who has pitched just 27 1/3 innings in 30 appearances this season after four straight seasons of 68 or more appearances – landed on the disabled list on Aug. 13 with a right rotator-cuff strain. That followed a right hamstring strain that shelved him for seven weeks.
"It's been a long time without him," Showalter said. "…It would be nice to get him back. We've been doing [it without him] for quite a while. … Other guys have stepped up and hopefully it will bode well for us, post-Sunday, if we can get Darren back, but I think to me, sheds light on what a good job the other guys have done because it's one of the better pitchers in the American League out of the bullpen; we haven't had him."
Around the horn: The Orioles' instructional league games in Sarasota – they will play from Monday to Oct. 11 at Ed Smith Stadium – will be free and open to the public. … The Orioles' 2017 schedule will be released Wednesday afternoon.