Roberts was replaced on Sunday at second base and in the leadoff spot by Robert Andino, who served as the second baseman while Roberts was out, and is hitting .239 this season.
Roberts is 7-for-22 since returning from his concussion, which had kept him out of action since last May. Showalter said that Roberts wasn't happy being out of the lineup, but he wants to use a cautious approach with the 34-year-old.
"It's not a whole lot of fun filling out a lineup without him in it," Showalter said, "but it's prudent at this point."
Roberts went 2-for-4 with three RBIs in the Orioles' 5-0 victory over the Braves on Saturday. Because the O's are playing in Atlanta under National League rules, two of his at-bats came with runners in scoring position after a sacrifice bunt by pitcher Jason Hammel.
"I told Hammel that's the fun part of National League baseball as a leadoff guy. When you have the bottom of the order swinging the bat good and the pitcher has a clue how to bunt, you get some RBI chances," Roberts said. "That's fun, because as a leadoff guy, that's not always your role."