“After the injury happened in February, Lance worked his tail off to get back on the mound,” Brown said in a statement. “This guy is a warrior and did everything in his power to get back. But each time he built himself up to an increased pitch total off the mound, the pain would come back. It’s unfortunate, but we look forward to him being back on the mound next season.”

Brown said the team did not have an exact timeline for when McCullers would return, but he could possibly start throwing again in November, and “then we will see in January where he is and how much he can get amped up.”

McCullers also missed most of last season because of the flexor tendon injury, going 4-2 with a 2.27 ERA in eight regular-season starts and 0-1 with a 5.87 ERA in three postseason starts.

“Lance is a grinder, and he tried to, with pure grit, fight through the injury and come back,” Brown said. “That happened in ’21, and in ’22, he ended up coming back some. You could give him cheers for his grit to come back. Starting out this year, he felt like he was going to be fine and continue to press through it and it continued to bother him.”

An All-Star in 2017, McCullers also missed the entire 2019 season after he underwent Tommy John surgery. The right-hander has spent his entire nine-year career with the Astros, going 49-32 with a 3.48 ERA.

The Associated Press contributed to this report.