Cubs reliever Julian Merryweather diagnosed with stress fracture in his rib

SAN DIEGO — Cubs reliever Julian Merryweather will be shut down from throwing for at least four weeks after imaging showed a rib stress fracture in his upper back, manager Craig Counsell revealed Monday.

The Cubs put Merryweather on the 15-day injured list Sunday with what they initially called a strained right shoulder, but he was scheduled to undergo further tests at the time.

‘‘Candidly, we thought it would be a little shorter stay on the IL, but that’s the breaks,’’ president of baseball operations Jed Hoyer said. ‘‘Obviously, we have to let him heal. ... Probably a little worse diagnosis than we had imagined, and we’ll just have to get through it.’’

Counsell said Merryweather’s injury hadn’t been a lingering issue. In his last outing Friday, he held the Dodgers to one hit in 1⅓ innings after entering with traffic on the bases and allowing only one inherited runner to score.

The last hitter Merryweather faced was Shohei Ohtani, whom he got to fly out. But he ‘‘felt something’’ on one of his last pitches, Counsell said.

‘‘Didn’t think much of it, frankly, after the outing,’’ Counsell said. ‘‘And then the next day it was sore, and the next day it was sore, as well.’’

Losing Merryweather disrupts the flow of the back end of the bullpen. In close games, Counsell typically has used Merryweather and Mark Leiter Jr. before turning to setup man Hector Neris and closer Adbert Alzolay.

In a right-handed-heavy bullpen, Leiter matches up well against left-handed-heavy pockets of lineups. Merryweather’s fairly even splits and ability to throw multiple innings gave Counsell flexibility in how he chose to use him.

‘‘Julian is a valuable reliever on this team, for sure,’’ Counsell said when asked about filling Merryweather’s role. ‘‘So I don’t see it being one person. You’ve got to close the hole around him, and a lot of people are going to have to fill into that spot. But it’s a significant loss, for sure. His versatility, just the quality that he brought, is going to be missed.’’

Hoyer addresses pitching injuries

A rash of high-profile major-league pitchers suffering elbow injuries has brought the debate about pitcher health to the forefront in recent days. During the weekend, the Guardians’ Shane Bieber and the Braves’ Spencer Strider were among the names added to a growing list of those with injuries to their ulnar collateral ligament.

‘‘It’s a real industrywide concern, and we’re part of the industry,’’ Hoyer said. “We have three pitchers on the IL right now that we were planning on playing a significant role. Three out of 13 guys, that’s a lot. I think for everybody it’s a real concern.’’

Those three pitchers are Merryweather, and starters Justin Steele (strained left hamstring) and Jameson Taillon (strained back).

This and that

• After throwing 52 pitches in 2⅔ innings during a rehab start Sunday for Double-A Tennessee, Taillon is set to continue his rehab assignment at Triple-A Iowa.
• Top prospect Pete Crow-Armstrong came out of the game Sunday at Iowa as a precaution, the Cubs said. He had soreness in his right (non-throwing) elbow from a dive in the outfield during a previous game.