"We were down to our last guy," Showalter said. "I was trying to stay away from Steve if I could. There's still somewhat of an option. We're going to have to think about it a little bit though and look at what other options we might have."
On Thursday afternoon, the Orioles announced Johnson as the probable starter for Saturday's game in Detroit, but Showalter said the team had other options at Triple-A if using Johnson on Thursday was unavoidable.
Triple-A Norfolk's scheduled starter for Saturday is Zach Britton, but the southpaw hasn't spent the required 10 days in the Minors following his Aug. 8 demotion. The only way he could be promoted is if he replaced somebody placed on the disabled list.
Jake Arrieta is scheduled to start for Norfolk on Friday.
Johnson was recalled from Triple-A on Aug. 8, earning the win in his first career start, as he allowed only two runs on five hits and two walks with nine strikeouts in six innings against Seattle.
He was then optioned back to Norfolk on Aug. 9 before being recalled on Tuesday to take the place of Troy Patton, who was put on the 15-day disabled list.
Despite the turbulent week, Johnson said the mental side of staying ready to pitch has not been an issue.
"I'm just going to pitch in the next couple of days, I know that much," Johnson said before Thursday's game. "Whether that's today, tomorrow or the next day, I'm ready for either one."
To try to stay physically prepared, Johnson has been skipping bullpen sessions in Norfolk, opting instead for the less-taxing long toss.
Johnson threw a few pitches off a mound on Wednesday "just to get a feel," but he has otherwise been working out to stay fresh.
"Whether it's going back in the bullpen, or spot start, or whatever it is, I'm ready for it," Johnson said.