"The physical part of it, Bud's fine," Showalter said. "The challenge will be the Cleveland Indians today. They have a lot of good left-handed hitters -- and right-handed hitters -- so he's making a big jump in competition. But I don't have any doubt that, physically, he's probably as good as he's been all year."
Norris pitched five innings Sunday, allowing one run on four hits while striking out seven.
He had struggled to begin the season, allowing at least three earned runs in all six of his first starts en route to a 9.88 ERA and the lowest strikeout rate of his career.
He was having trouble repeating his arm slot, which led to worsened command of his slider, which serves as his main secondary pitch.
"I think one of the keys for him will be the first inning, to just get that motion under control," Showalter said.
As a result, the slider was finding itself elevated more than Norris would like, leading to less swings-and-misses and more fly balls.
"He wasn't real happy with his slider before, and in a couple of his [rehab] outings, he had a really good one," Showalter said. "Not only was he saying it, but the people that were there were talking about it."
To make room for Norris, the Orioles optioned infielder Rey Navarro back to Triple-A Norfolk. They will play with a shortened 24-man roster until reliever Brian Matusz is finished serving his eight-game suspension on June 13.
August Fagerstrom is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.