"We're going to err on the side of carrying the arms, especially protecting the bullpen until guys kind of find their step as starters," said manager Buck Showalter. "Rick [Adair] and I spent a lot of time, mostly leaning with what Rick thinks, about protecting some of our guys' innings, because we want to make sure we've got all of our bullets as we go through the season. I'm sure we'll go back to a four-man bench at some point."
Showalter said the team would have kept the roster constructed as such even if they didn't have pitcher T.J. McFarland, one of three left-handers in Baltimore's bullpen who must stay on the roster or the Orioles lose him due to his Rule 5 Draft status.
Tillman was slowed earlier this spring with an abdominal injury and last pitched on March 29 against the State College of Florida. Because it wasn't an official Grapefruit League game, the Orioles were able to backdate his DL stay to have him eligible for Saturday's start.
Navarro, 25, was recalled from Norfolk on Friday, but did not play. He was acquired from Pittsburgh in November after hitting .279/.366/.491 in 66 games with Triple-A Indianapolis last season and going 8-for-50 with the Pirates.
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.