The Brewers placed former All-Star closer Corey Knebel on the 10-day injured list Thursday with a strained left hamstring, marking a setback in Knebel’s comeback from missing all of last season after undergoing Tommy John surgery.

The pandemic robbed Knebel of a chance to complete his rehab from April 2019 surgery with tune-ups in a Minor League setting, and while it’s unclear whether mechanical issues stressed the hamstring or the hamstring led to mechanical issues, it was time for a break. Knebel inherited a 9-1 lead in the ninth inning of Wednesday’s win over the Twins and was unable to get through it, allowing a home run for the fourth time in his last six outings.

Milwaukee promoted infielder Mark Mathias from the alternate training site to take Knebel’s spot on the active roster.

“One thing Corey has been really consistent about is, ‘My arm feels good, my arm feels good,’” manager Craig Counsell said. “But he has gotten into some mechanical issues, he thinks, also. This hamstring, maybe it’s kind of one of those things where it may be causing some of this.”

Fellow Brewers right-hander Adrian Houser can empathize with the ups and downs of Knebel’s comeback, having had the same elbow surgery four years ago. The difference in 2020, Houser said, is that “[Knebel is] coming in there and facing the best hitters in the game.”

Hitters are winning the battle so far. Knebel’s four-seam fastball is averaging 94.1 mph in nine appearances this season, down from 97.3 mph in 2017 when Knebel was a National League All-Star, and 96.9 mph in '18 when he was arguably more valuable than Josh Hader in September and October for a Brewers team that played to within one victory of the World Series.

Houser, who is scheduled to start for the Brewers on Friday in Pittsburgh, had the surgery in July 2016 and was back on the mend in the lower levels of Milwaukee’s farm system by the end of ’17, prior to a stint in the Arizona Fall League.

Some days, Houser felt great. Other days, his arm felt lousy. And then there were the days he felt “really good, but you don’t know where the ball is going.”

Houser said he and Knebel have had a few conversations about it.

“I’m sure he’s getting frustrated because I know I was getting frustrated the year I came back from Tommy John,” Houser said. “You feel good and stuff just isn’t happening like it should or how you want it to. At first, I kind of disagreed with people who said [it wouldn’t feel back to normal until Year 2]. I thought the way I was feeling through my rehab, the first year would be no problem. But it definitely had its challenges.”

And that all happened in the Minor Leagues.

Knebel is charting the same course in the Majors. He will remain with the Brewers through the remainder of their road trip. When he’s ready, he will pitch some innings at the team’s alternate training site in Appleton, Wis.

“It’s going to be a little harder for him,” Houser said. “We’re all here to support him and help him get through this.”

Hiura, Counsell have a conversation
Keston Hiura atoned for a first-inning mental lapse in Wednesday’s 9-3 win by finishing 3-for-4 with a home run. In his first at-bat, Hiura followed Christian Yelich’s one-out single with a popup on the infield and didn’t hustle to first base. Twins second baseman Ildemaro Vargas alertly let the baseball drop, then began an easy double play to end the first inning, with Hiura nowhere near first base.

"He screwed up. There's no question about it,” Counsell said. “We had a conversation about it, both during the game and after the game. And we're clear on it. But he screwed up."

Hiura, who was serving as the designated hitter, remained in the lineup and his night got better. In the third inning, his two-out single kept alive an inning that turned into a four-run rally. Then he walked in the fifth, singled again in the sixth and homered in the ninth off Twins infielder Ehire Adrianza. Hiura’s sixth home run kept pace with Christian Yelich for the team lead.

Henry joins player pool
The Brewers added catching prospect Payton Henry to the 60-man player pool on Thursday and assigned him to the alternate training site. Henry, ranked Milwaukee's No. 17 prospect according to MLB Pipeline, was a non-roster invitee to big league Spring Training, but he was not initially included in the team’s player pool when baseball resumed in July.

Why wait more than a month and a half to add him to Camp Appleton? Several factors could be in play.

One is that the 2020 Trade Deadline is looming on Aug. 31 at 3 p.m. CT, and the only players eligible to be traded this season are those who are in a team's 60-man player pool. Many teams have left spots open in order to preserve flexibility to make additions closer to the Deadline as they work to identify potential trade partners. Just last week, Milwaukee added its No. 9 prospect, outfielder Hedbert Pérez, to the pool.

Another possibility is that the catchers already in Appleton -- Thomas Dillard, Mario Feliciano, David Freitas and Jacob Nottingham -- have carried a significant workload during daily workouts and scrimmages. Adding Henry helps share that workload, and it lets one of the organization’s top prospects get some live at-bats rather than lose a whole season of development.

Henry, 23, hit .242/.315/.395 with a career-high 14 home runs last season at Class A Advanced Carolina.