Given how late it is in camp, it's probably safe to say that Johnson, who had an outside shot to break with the Opening Day team, will likely start the season with Triple-A Norfolk.
The Orioles are also mulling over whether to place right-hander Chris Tillman on the disabled list to start the season. The stint would be backdated to his last spring start, which was March 3. The team has floated the idea to Tillman, who is a little behind after dealing with some abdominal soreness, and a move would open another roster spot.
It could also allow the Orioles to keep Rule 5 Draft pick T.J. McFarland, who Showalter confirmed will likely only make the team in a long relief role. That would free up right-hander Tommy Hunter, should he make the club, to be used in another role, and also give them two lefties -- Brian Matusz and Troy Patton -- to use in the later innings.
"If that's the direction we go," Showalter cautioned reporters. "That's still a tough bite. I just don't know if we are going to be able to take [McFarland]. It's going to be close. Have to get some help from other organizations [and potentially make a trade]. I don't know."
Hunter allowed three earned runs in 1 1/3 innings in relief on Tuesday.
The Orioles need a fifth starter only once before April 21 and could use their early off-days to manipulate the rotation with four pitchers to create another roster spot. Matusz, who has been stretched out as a starter this spring, could be a candidate to make a spot start if they go that route, which would involve putting Tillman on the DL.
Jake Arrieta appears to be the guy who will win the rotation spot with Jason Hammel, Wei-Yin Chen and Miguel Gonzalez also penciled in. However, if he's deemed healthy, Tillman, who is out of options, will be in the rotation.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.