Hardy is sidelined with a left groin injury that had been nagging him for several days prior to the team making the injury public on Sunday. Manager Buck Showalter said he was encouraged with the results of Hardy's MRI and the All-Star will rejoin the team on Tuesday at Kauffman Stadium to continue his rehab.
"You always miss what he brings on the field, his leadership out there," Showalter said. "It's got to the point where if we didn't try to get this cleared up in two weeks ... Otherwise, he's going to have a problem all year. Got a chance to get it resolved and come back for the last four weeks of the season. We hope the playoffs, and he can be healthy for that."
The All-Star shortstop admitted Sunday that he'd been dealing with the injury for a while, and Hardy was batting .157 (11-for-70) in August.
"We tried to get through it, see if he was going to get better, but it's something that's going to nag him the rest of the season if we don't take chance to try to clear it up," Showalter said. "He'll be missed."
Pearce, 32, was on the DL with a left oblique strain, and he played two games for Double-A Bowie and two with the O's Gulf Coast League team while on rehab.
"I had about 25 at-bats before I got here so it wasn't like I'm getting thrown straight into the fire," said Pearce, who was hitting .227 (40-for-176) with seven home runs and 24 RBIs in 58 game for the O's entering Monday.
"It feels great to be back. I've been out a month. I definitely missed being here. I missed being with the guys, and I'm glad to be back."
The 27-year-old Rondon has gone 3-1 with a 2.42 ERA in 29 relief appearances with Triple-A Norfolk this season. He made one relief appearance with Baltimore on Aug. 2, when he tossed 3 1/3 scoreless innings against the Tigers.
Reimold appeared in just 39 games for the Orioles this season, batting .227 (22-for-97), with three doubles, one triple, two home runs and eight RBIs.
"We'll see if he's not claimed that he'll come back to us," Showalter said. "We feel like there's a chance that will happen."
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, follow her on Facebook and Twitter @britt_ghiroli, and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.