SAN DIEGO — The Chicago Cubs expected to get a boost sometime in the next few weeks with the return of left-hander Justin Steele.

However, a setback during the build-up process has significantly pushed Steele’s original timeline for his comeback from last April’s left elbow surgery. Steele has been diagnosed with a flexor strain and will be re-evaluated in one month, manager Craig Counsell said Tuesday.

Steele is now unlikely to rejoin the Cubs’ rotation until after the July All-Star break, Counsell estimated.

Steeled planned to go back to Dr. Keith Meister for a final check-up to continue with the rehab process for his elbow, but he didn’t feel great throwing a bullpen over the weekend. That prompted an MRI on Tuesday morning, which revealed a flexor strain. The imaging encouragingly showed no damage to his ulnar collateral ligament (UCL). Steele will be shut down from throwing until he is asymptomatic.

“More than anything, for Justin it’s just frustrating,” Counsell said. “During the course of these rehabs, there are always good days and bad days that you navigate through it. But when you start getting back to where Justin was and getting fairly close to kind of getting back into competition, you think you’ve kind of crossed some of those. And unfortunately, we’ve just hit another speed bump here, and it’s going to take longer.

“The rehab process is long and monotonous at times and when you’re close to the end and you get told, ‘No, we’re back into rehab mode,’ that’s tough. … We’re going to get less of him this year, but still plenty of time to get back for this year.”

The Cubs anticipated Steele’s rehab wouldn’t go perfectly smoothly, given the nature of the surgery he was coming back from. But this new injury prevents Steele from returning in late May or early June. Steele had been facing hitters in live batting practice since March and was getting close to starting his minor-league rehab assignment.

Steele, 30, hasn’t pitched in a big-league game since April 7, 2025. He is currently one of 11 Cubs on the injured list, including 10 pitchers. Lefty reliever Riley Martin is also dealing with a flexor strain, which will keep him out about two months. The Cubs have also lost right-handers Cade Horton and Porter Hodge to Tommy John surgery this month.

“When you have a lot of injuries, of course we try to examine everything we’re doing — I think that you should,” Counsell said. “When you’re having success, struggles, the same injury, absolutely you try to make sure your processes are good and you’re not doing anything that would, I don’t want to say create injuries, but make players more exposed to injuries.”