CHICAGO -- The Tigers’ recent rash of injuries left them with former White Sox second baseman Gordon Beckham as their regular shortstop for most of the past couple of weeks, including a pair of series against his old club. Starting Tuesday, the Tigers should be in a cycle of getting injured players back, beginning with starting shortstop Jordy Mercer.

Mercer, out since May 14 with a right quad strain, is scheduled to finish up a rehab assignment at Class A Advanced Lakeland, then join the Tigers in Philadelphia in time for Tuesday’s series opener against the Phillies.

It’ll be a welcome addition for a club that currently has six players on the injured list, including three-fifths of its original starting rotation. It should also free up Beckham to return to a utility role and give Josh Harrison a day off here and there.

Harrison was scratched from Sunday's game with a left shoulder contusion.

“He dove the other day up the middle and kind of messed his shoulder up a little bit,” manager Ron Gardenhire said, “but he’s fine. He came in [Saturday] and did all his work.”

Mercer entered Sunday batting 0-for-11 with a walk and three strikeouts at Lakeland, but it isn’t the offense the Tigers are missing. His stability at shortstop is the key. He already has one Defensive Run Saved, according to FanGraphs.

The Tigers cleared a roster spot for Mercer’s expected return after Sunday’s 4-1 loss by optioning outfielder Dustin Peterson to Triple-A Toledo. Gardenhire said the Tigers want Peterson to get regular at-bats as well as to begin working at first base.

Tigers go with four-man rotation
Ryan Carpenter was in the Tigers' clubhouse Friday afternoon, preparing for a Saturday start he knew might not take place given the forecast. Once Saturday’s game was postponed, Carpenter was gone. On Sunday, the left-hander was the starting pitcher for Triple-A Toledo on the road in Gwinnett, Ga.

No roster move was needed, since Carpenter was never officially recalled from the Mud Hens. From a transactions standpoint, it’s as if he was never here. From a scheduling standpoint, there’s a good chance he’ll be back soon.

The Tigers have just four starters for now with Jordan Zimmermann on the injured list for at least the next 3-4 weeks. But with four off-days in a 10-day span, including Saturday’s postponement, Detroit can keep its four starters on regular or extra rest without needing a fifth starter until May 11 at Minnesota.

“We’re going to try to keep the guys that are still here on that normal rest,” Gardenhire said. “But there’s no guarantees with it. We don’t even have a fifth starter right now on this roster. We’ll just make the adjustment as we go on the fly.”

The Tigers made one minor adjustment for their upcoming two-game series in Philadelphia, flipping Tyson Ross and Spencer Turnbull in the rotation order. Ross will start Tuesday’s series opener, followed by Turnbull on Wednesday.

The problem when the Tigers need a fifth starter on May 11 is that they’ll also need a sixth starter that day. They have a doubleheader to make up for their snow-out in Minnesota two weeks ago.

The Tigers could call up two starters for that day -- left-hander Matt Hall is the other Mud Hens starter currently on Detroit’s 40-man roster -- or they could use a spot starter. They could even use an opener, Gardenhire acknowledged.

Any of those roles could be where versatile left-hander Blaine Hardy, currently on the 10-day injured list with a left forearm strain, comes in. Gardenhire and pitching coach Rick Anderson have discussed the idea of using Hardy again in a starting role; he made 13 starts under similar circumstances last season with moderate success.

“He might be our best option,” Gardenhire said. “But he’s hurt. It’s hard to stretch a guy out when he’s coming off the IL.”

Hardy is flexible with it.

“Just kind of roll with the punches,” he said.

Quick hits
• Tigers left fielder Christin Stewart headed to Lakeland on Sunday to pick up his rehab from a right quad strain. He’s not ready just yet to begin a rehab assignment, but he’ll be able to take fly balls and pick up baseball activity in warmer conditions. “He’s not ready to go play defense yet or anything like that,” Gardenhire said, “but he feels good.”

• Thanks to a weather postponement on Friday, top prospect Casey Mize will make his Double-A Erie debut on Monday at Altoona, rather than Sunday as originally scheduled. The SeaWolves have lined up Mize, Matt Manning and Alex Faedo back to back to back.