Kyle Harrison’s performance for the first two months of the 2026 season signaled yet another win for the well-regarded Brewers pitching lab. We sure thought so, anyway.
After being acquired in a trade with the Red Sox, the left-hander came out of the gates as one of MLB’s best starters, posting numbers that nearly rivaled eventual National League Cy Young Award winner Jacob Misiorowski’s stats in the early going.
But Harrison’s numbers quickly regressed, and a brutal end to the season -- which followed a stint on the injured list with a forearm issue -- left him with a 4.20 ERA in 115 2/3 innings when all was said and done. Although he made the roster for each round of the postseason, he didn’t appear a single time in October as the Brewers went on to win their first World Series championship.
Given his sudden ineffectiveness, it’s fair to question which Harrison the Brewers will get in 2027: the one who looked like an ace alongside Misiorowski and Logan Henderson at the top of Milwaukee’s rotation, or the one who was moved to the bullpen late in the year among continued struggles?
Here’s a look inside Harrison’s up-and-down 2026 and what the Brewers can expect from him next season.
A stellar start
Harrison earned a spot in the Brewers’ Opening Day rotation and ran with it, dominating hitters through the first two months of the season and into early June. In his first 11 starts, he had a 1.57 ERA with 16 walks and 73 strikeouts in 57 1/3 innings, ranking second in MLB (min. 50 innings pitched) in strikeouts per nine innings and third in ERA.
Harrison, who split time between starting and relieving in the big leagues with the Giants and Red Sox in 2025, wasn’t going deep into games: He made just one start longer than six innings and averaged just 5.21 innings per outing. But he was fantastic on a per-inning basis, racking up double-digit strikeouts in three of those 11 starts and carving up hitters with a four-pitch arsenal led by a fastball with one of the highest usage rates in the big leagues.
MLB Pipeline’s No. 20 overall prospect at the time of his August 2023 debut for San Francisco, Harrison had a 4.39 ERA in the big leagues prior to 2026. His early success with the Brewers appeared to confirm his breakout and cement him as a top-of-the-rotation arm alongside Misiorowski (and later Henderson), a big development for the Brewers at the time considering Brandon Woodruff’s lingering shoulder issue.
But in his 12th start of the season, on June 8 against the Athletics -- albeit at the veritable launching pad of Las Vegas Ballpark -- Harrison was tagged for eight runs in just 2 1/3 innings, inflating his ERA by more than one full run.
He followed the blowup outing with three strong starts, but after allowing six earned runs in 6 2/3 frames in two early-July games, Harrison landed on the 15-day IL with left forearm tightness. He didn’t return until Aug. 5, and when he did, his struggles continued.
A tough ending
Although Harrison’s first start after returning from the IL was excellent -- he allowed just one hit over five scoreless innings, striking out 10 -- he soon fell out of Milwaukee’s starting rotation. Of his final five outings of the season, four were out of the bullpen and one was a start of just 1 2/3 innings. In August and September, Harrison had a 7.31 ERA in 32 innings of work.
So what happened? That is the question, and Harrison’s arm injury is at least part of the answer. His average fastball velocity dipped from 95.0 prior to his IL stint to just 93.7 mph in August before rebounding to 95.2 mph in September. Need a sign Harrison was hampered physically? The lefty’s average arm angle dropped to 31.9 degrees after he returned, compared to 33.4 degrees beforehand. A decrease such as that is often a sign of a pitcher pushing through an injury.
Although the forearm issue seems to have affected Harrison, the movement on his fastball had been a concern well before he was placed on the IL. Harrison averaged 15.1 inches of induced vertical break, AKA the apparent “rise” on a fastball, during his first 11 starts and just 14.4 inches of IVB after that. Harrison found it harder to miss bats, as the whiff rate on his four-seamer dipped from 31.6% to 23.0%.
“The heater hasn’t been as ‘poppy,’” Harrison told MLB.com in September. “I’m feeling good, but I need to dial that thing in.”
It wasn’t just his fastball: Harrison was hit hard overall for much of 2026, a stretch that put a damper on his outstanding start.
Harrison’s batted-ball metrics through June 2 (11 starts)
5.1% barrel rate
28.5% hard-hit rate
87.6 mph avg. exit velocity allowed
Harrison’s batted-ball metrics from June 8 on (17 games, 13 starts)
10.4% barrel rate
46.4% hard-hit rate
89.8 mph avg. exit velocity allowed
Those endpoints are admittedly arbitrary, but it’s fairly clear to see when Harrison first began to struggle in 2026 -- more than a month before forearm soreness sidelined him.
2027 outlook
Regardless of results, one concern for the Brewers is Harrison’s inability to get deep into games, especially late in the year. The last time he completed more than five innings was June 20, and he averaged just 3.5 innings per appearance after that point.
The Brewers are certainly fortunate Harrison’s forearm soreness -- often indicative of a more serious injury in pitchers -- was mild, and they must be glad to know the lefty felt good physically at the end of the year.
Additionally, Harrison’s struggles were exacerbated by a bit of bad batted-ball luck: His .333 expected wOBA from June 8 on was considerably lower than his .400 wOBA. While he was a bit lucky before that point (.260 wOBA, .278 xwOBA), Harrison ended 2026 with a 4.01 expected ERA, compared to his actual 4.20 mark.
Interestingly, Harrison’s 2026 results pretty much fell in line with his prior performance, although there was definitely a bit more variance involved in his fourth big league season. Both he and the Brewers will be hoping for a lot more consistency going forward from the talented left-hander.
If that happens, and Harrison routinely performs like he did early in 2026, watch out: The Brewers’ 1-2 punch at the top of their rotation might just become a 1-2-3 trifecta.