Roberts went 0-for-4 with two strikeouts and a walk in his first action with the IronBirds.
"The length [of his rehab assignment] would only come into play if he would have had to have surgery," Showalter said of Roberts, who will likely need the procedure, but is hoping to play through the injury until the offseason.
"There's a different level down there, [in extended spring training] there's a different level in Aberdeen than up here. So we will take all the things that we can take in, and I think Brian will be honest with us. He knows what it takes to play here. Would obviously be a nice addition to get him and Robert Andino back."
The plan is for Roberts to play Saturday and Sunday -- getting a minimum of three at-bats Saturday -- and the expectation is he will play close to, if not all, of the game.
"I don't think there's a limitation," Showalter said. "Because if there is, then that probably doesn't tell you anything you want to know."
The 34-year-old Roberts had been working out at the team's spring facility in Sarasota, Fla., and met with Showalter in his office in Baltimore on Saturday afternoon before heading to Aberdeen. Roberts has played in just 17 games this season, making his season debut on June 12 after being activated from the 60-day disabled list following a concussion. It was a triumphant return -- he went 3-for-4 with an RBI in his first Major League game since May 16, 2011. But he struggled to keep up that momentum, hitting the DL -- with what was originally deemed to be a groin strain -- with a .182 batting average, five RBIs and two runs scored.
Asked what Roberts' return would do for Nick Markakis in the leadoff role -- a spot Markakis has flourished in -- Showalter declined to answer until the second baseman returns.
"He's obviously had the most experience," Showalter said. "And like I've said, Nick is capable of hitting anywhere in the order, in my mind, where Brian is not."
It's a decision Showalter hopes to make soon. With Andino slated to start a rehab assignment Sunday -- and a possible return as early as Tuesday -- adding Roberts would further bolster a depleted Orioles infield.
"Brian basically is saying I want to come help the club now, if I can manage this and get through it," Showalter said. "If it's just a matter of tolerating if it's just discomfort he's in. But, if it's something he can't function with at all, then he will proceed with the surgery."
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.