Brewers' Kyle Harrison postseason roster decision anything but certain after encouraging signs

It has been a tumultuous second half of the regular season for Milwaukee Brewers' starting pitcher Kyle Harrison. The 25-year-old southpaw was among the best starters in baseball during the first half of the season while assuming the No. 2 role in Milwaukee's rotation behind ace Jacob Misiorowski. However, ever since a bout of forearm tightness kept him on the IL from early July to early August, Harrison hasn't shown the same dominance on the mound.

It feels clear now that Harrison, who has maintained that he feels fine despite his dip in effectiveness and velocity, was battling some normal arm fatigue and inadvertently changed his mechanics to combat it. A lower arm slot and less bend in his legs have been cited as mechanical changes that are causing Harrison's recent inconsistency. Said inconsistency has led to a 7.80 ERA in 10 appearances (seven starts) since Harrison returned from the IL on August 5.

These recent struggles have led to a larger debate about Harrison's role on the Brewers' postseason roster. Milwaukee has already punched their ticket to the postseason and secured a first-round bye last night, but their playoff pitching staff is far from set. Whereas Harrison looked like the Brewers' obvious Game 2 starter for the first half of the season, his ineffectiveness during the second half has led to questions of whether or not he even belongs on the postseason roster.

Those questions appeared all but answered after Harrison's start against the Pittsburgh Pirates last Thursday. The southpaw lasted just 1.2 innings, surrendered four earned runs on four hits, walked two batters, and hit two more. While manager Pat Murphy maintained that the Brewers were going to continue to give Harrison opportunities to prove himself, the outlook appeared bleak for the struggling left-hander.

However, in Harrison's two relief appearances since his rough start in Pittsburgh, the once-dominant southpaw has shown signs of encouragement that prove the Brewers' decision of whether or not to include him on the postseason roster could come down to the wire.

Kyle Harrison's fastball shape has been restored, but command and slider shape remain worrisome

One of the reasons Harrison was so dominant through the first three months of the 2026 season was an improved shape on his four-seam fastball. The Brewers raised Harrison's arm angle during the offseason, which, in turn, improved his spin efficiency and caused the rising movement on his four-seam fastball to increase compared to past seasons. Whereas Harrison's four-seam averaged just 12.4 inches of induced vertical break (IVB) during the 2025 season, the left-hander consistently sat in the 15-16 inch range during the first half of the 2026 campaign. That change not only made his fastball more effective, but it also allowed his relatively shallow breaking ball, which Statcast deems a "slurve," to play up.

However, as Harrison's arm fatigue set in, his arm angle dropped and the rising action on his fastball decreased. Over the last month or so, Harrison was averaging closer to 13-14 inches of IVB, which may not sound like a big difference, but baseball is, in fact, a game of inches. At the same time, Harrison's slurve also lost depth, meaning the difference between his fastball and breaking ball was far less and therefore easier for opponents to handle.

In each of Harrison's last two outings, however, the ride on his fastball has returned. During his 20-pitch outing against the Baltimore Orioles on Sunday, Harrison averaged 15.2 inches of IVB on his four-seam, and in last night's inning of work against the Phillies he averaged 16.3 inches of IVB, which is the most he's averaged in a single outing all season. Pair that with the fact that the velocity on his four-seamer has been restored over his last four outings, and there are undeniably reasons to be encouraged about Harrison's recent appearances.

That said, even with the restored fastball shape and velocity, Harrison didn't get the results he was hoping for last night. For that, there are two main reasons: fastball location and the shape of his slider. While Harrison's fastball now resembles the one he was throwing at the beginning of the season, he isn't commanding it at the top of the zone like he did before the All-Star Break. His rising fastball plays best at the top of the zone, but Harrison's recent location plots don't indicate he's able to spot the ball there like he did earlier this year.

Additionally, the depth on Harrison's breaking ball still hasn't returned. Take, for example, the pitch that Alec Bohm roped into the left field corner for an RBI-double last night. It wasn't a poorly located breaking ball from Harrison -- it was several inches below the zone -- but the pitch only had -2 inches of IVB. Earlier in the season, Harrison was averaging as much as -6 or -7 inches of IVB with his breaking ball. That difference is what allowed Bohm to get to a well-located breaking ball last night, whereas earlier in the year he likely would have swung over the top of it.

The Brewers and Harrison have already overcome one hurdle: restoring the shape and velocity of his fastball. Their ability to overcome the remaining two hurdles -- fastball location and the shape of is breaking ball -- will ultimately determine whether or not Harrison is included on the postseason roster. Milwaukee's first postseason game will take place on October 3, so Harrison and the Brewers' excellent pitching coaches have 10 days to solve the remaining challenges and restore the once-dominant southpaw's effectiveness.

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