"A fatigue and tightness kind of thing," Norris said of the elbow issue, which cropped up last month in Arizona. "There was no specific day. Obviously getting to this point in the season, we're adding up and so forth. I definitely felt it in my last couple [games], but I wanted to go out there and compete."
The decision came to skip him after Norris felt his elbow bark up again during Wednesday afternoon's work day.
"We want to back off and treat it," manager Buck Showalter said. "You're always working on your next start and there's some things that guys do. I think talking to Bud and to trainers, I think it would be best to stay away from all the work that starting pitchers do to get ready for their fifth day and just let it quiet down. It managed itself well the last time, so we want to get back to that. I think you'll see him pitch again for us."
Norris is 10-11 with a 4.12 ERA in 30 games, 29 starts, between Houston and Baltimore this season.
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.