When Pittsburgh Pirates manager Derek Shelton said Thursday was the most important day of Mitch Keller’s rehabilitation from an oblique injury, it wasn’t based on how the right-hander performed.

Instead, the focus is on how Keller feels the day after throwing a three-inning, 43-pitch live batting practice session at PNC Park, the penultimate step in returning to the starting rotation.

Pirates director of sports medicine Todd Tomczyk compared it to a minor league rehab start and said Keller is “checking off all the boxes” to be medically cleared to come off the injured list.

“From there, we’ll make the determination,” Shelton said, “but I expect him, if he’s good and feels good, that we would move him back in the rotation in some spot.”

That’s a big step for not only Keller but the Pirates, who view the 24-year-old as a future staff ace. They love his stuff, even if they haven’t seen enough of it at the major league level. He entered the season as the organization’s top prospect but has pitched only 7 2/3 innings and has been on the IL since Aug. 2. In 13 career starts, Keller is 2-6 with a 6.63 ERA and 1.78 WHIP but an impressive 11.0 strikeouts per nine innings.

Pirates pitching coach Oscar Marin was impressed with the way Keller battled despite not being at his best in his first start, a 5-1 win July 26 at St. Louis. Keller changed speeds and eye levels on his pitches in allowing one run on two hits and three walks with two strikeouts.

Keller, however, was removed from his second start after giving up two home runs and a single in the third inning against the Chicago Cubs on Aug. 1 at Wrigley Field, so he has pitched only 7 2/3 innings this season.

What has been beneficial to Keller is how much time he has spent with Jameson Taillon, who is recovering from Tommy John surgery. It has allowed Keller to pick Taillon’s brain on pitch selection and sequencing, how to attack hitters and how to prepare in between starts.

“Being on that rehab process with Jameson Taillon probably has been the best thing for him,” Marin said. “They talk every single day. They watch the games together, and certain situations that come up during the games, they’re talking about it. I mean, what better influence to have than having Jamo with him? Those are the kind of things that have helped him out. And just from our side is every time he has thrown a bullpen or he throws a live BP, we’re talking him through the situations: ‘Hey, what was the thought process behind that pitch? What’s your thought process in the location of this one?’ Just having him understand different things so he can keep growing, even without the reps in the game.”

Marin is pleased with Keller’s progress, noting “the life on the fastball hasn’t gone away” and that his breaking balls look sharp. In the meantime, the Pirates have worked with Keller on his mechanics to prevent the injury from recurring.

“One of the things that our rehab team has done with him is really try to maintain his posture down the slope,” Marin said. “He had the oblique that shut him down, so one of the postural things that we identified was maintaining his posture down the slope. He’s been doing a really good job and he’s bought into it.”

What Keller has to do now is prove he is finally healthy. His final test is about recovery, with a bullpen session likely determining if he is ready to return. Then it’s up to Shelton and Marin to decide when Keller will make his next start, likely sometime early next week.

The Pirates have Steven Brault, Trevor Williams and Chad Kuhl slated to start this weekend in Kansas City, then play a doubleheader Monday at the Cincinnati Reds. Joe Musgrove and JT Brubaker are lined up for their next starts — and Musgrove would be pitching on five days’ rest — but that could change if Keller is ready to return.

Having a full complement of starting pitchers will be something new for Shelton, even if Musgrove and Keller are still building up their pitch count. It will give the Pirates a glimpse in the final three weeks of the season of what their future starting rotation could look like and, perhaps, bolster their bullpen.

“Just being able to watch some of his live pitching, it’s awesome to watch,” said Brubaker, who relieved Keller against the Cubs and then replaced him in the starting rotation. “Ready for him to get back, join the rotation, go out there and compete. It’s always fun to watch Mitch pitch from the dugout or, this year, in the stands. It’s going to be very enjoyable once he gets back.”

Copyright ©2025— Trib Total Media, LLC (TribLIVE.com)