While starting pitchers are not as volatile as relievers, injuries and underperformance have left many with rough seasons in 2025. Tonight we look at three rebound candidates: a top free agent, an experienced starter and a minor league acquisition.
Best Free Agent: Zac Gallen
Gallen was a front-of-the-rotation arm at best. From 2022-2023, he posted a 3.04 ERA in 394 innings pitched for the Diamondbacks. He struck out 26.4% of batters in that span and ranked eighth among qualified starters with a K-BB percentage of 20.4%. His 9.3 fWAR ranked sixth, ahead of the Giants ace Logan Webb. Entering his age-28 season in 2024, there was reason to believe Gallen would continue to pitch at his peak level.
His numbers were still solid that year, although it was a step back from top territory. Gallen missed a month with a right hamstring strain, but still made 28 starts with a 3.65 ERA. He even increased his groundball rate from 41.8% in 2023 to 46.2% in 2024. That said, his strikeout and walk rates both trended in the wrong direction, with the latter now closer to average after two years of excellent control. Gallen slumped further in 2025. Although he stayed healthy and logged 192 innings in 33 starts, his ERA jumped to a career-high of 4.83, his first below-average mark since 2021. The strikeouts fell further to 21.5%, while his expected stats (4.28 xERA) suggest he was better than the surface numbers, but not by much.
Gallen entered the offseason as a buy-low candidate, as far as former aces are concerned. We at MLBTR projected him to get a four-year, $80 million contract even after his down year. Ultimately, his market did not develop as hoped. Gallen settled for a one-year, $22.025 million reunion with Arizona, which nominally matched the value of the team’s qualifying offer in November.
The team would obviously like to see him return to his 2022/2023 form. Gallen expects to deliver at least 30 starts of mid-rotation production, though he will undoubtedly aim for more in hopes of landing a multi-year contract next time around. The key for Gallen will be refining his breaking pitches, which ranked poorly in 2025 according to Statcast’s run value metric. His curveball was worth 15 runs above average in 2024, but that dropped to -4 this year, with opponents over .200 more on the field. He’ll also look to drive up the strikeouts and keep the ball in the yard after allowing the third-most home runs (31) of any qualified starter in 2025.
Veteran starter: Sean Manaea
Manaea re-signed with the Mets on a three-year, $75 million deal during the 2024-2025 offseason. At the time, he was coming off a strong 3.47 ERA in 181 2/3 innings in his return to full-time starting pitching (after primarily being a reliever for the Giants in 2023). With New York in 2024, Manaea struck out hitters at a 24.9% clip and did a decent job keeping the ball in the yard compared to his career numbers. His .249 BABIP suggested he was benefiting from luck, but he still thought he offered solid, mid-rotation value on his new deal.
Unfortunately, his 2025 season was the exact opposite of his 2024 season. Manaea went down in March with a right oblique strain and missed the first three and a half months of the season. At one point he suffered a setback when the team found loose bodies in his throwing elbow. He finally made his debut on July 13 and made 15 appearances (12 starts) with an ERA of 5.64. Oddly enough, he posted that high ERA despite striking out 28.5% of his career batters and striking out a career low 4.6%. Meanwhile, his expected stats (4.00 xERA and 3.30 xFIP) painted a much better picture than his superficial numbers.
On the other hand, Manaea struggled with the long ball in 2025, allowing 13 in just 60 2/3 innings (1.93 HR/9). Curiously, he also dropped his sinker, which was worth ten runs above average in 2024, to instead throw his four-sieve more than 60% of the time. Opponents scored .129 higher against the four-seamer compared to 2024, when he used him half as much. Manaea also increased the use of his sweeper, but saw diminished results, including a 9.6% drop in strikeout rate and a .148 increase in slugging.
Maybe that was a mechanical problem. Manaea adopted an underarm lock in 2024 and had a very productive second half. The combination of his oblique injury and further attempts at mechanical adjustments may have contributed to his poor 2025 numbers, Mets manager says Carlos Mendoza (link via Alex Smith from SNY). The keys for him in 2026 are regaining his pre-injury mechanics, differentiating the two fastballs like he did in 2024, and continuing to chase the sweeper.
Minor League signing: Walker Buehler
The current version of Buehler is a far cry from the one who finished fourth in the NL Cy Young voting in 2021. The now 31-year-old has thrown 266 1/3 innings since the end of that campaign. He missed all of 2023 while recovering from Tommy John surgery in August 2022. He returned for 16 starts in 2024, but the results were decidedly poor. Buehler struck out just 18.6% of batters against an 8.1% walk rate and allowed nearly two home runs per nine innings. His once vaunted four-seater was now his least valuable pitch at 13 points below average. However, Buehler pitched well in the postseason for the World Series-winning Dodgers. The Red Sox then took a gamble on a one-year deal worth $21.05 million.
Unfortunately, 2025 wasn’t kind to him either. Buehler threw 126 innings in 26 appearances (24 starts) with an ERA of 4.93. His velocity was lower on every throw except his slider. His strikeout rate dropped to just 16.3%, while his K-BB rate of 5.5% was fifth-worst among starters with at least 100 innings pitched. Boston released him in late August. While he did well in a small sample size with the Phillies afterward, it was clear that Buehler wouldn’t do nearly as well on the market this time around.
Now competing for a back-of-the-rotation spot in San Diego, Buehler will have to work hard to regain some value. He could start adjusting his pitch mix. He has already steadily reduced his use of four seams as it continues to lose speed. Meanwhile, Buehler’s 2025 sinker was highly ranked by Statcast, six runs above average. Making the sinker his primary fastball will help him develop into a soft-contact groundball pitcher. His hard-hit percentage and average exit velocity were in the 70th percentile or better in 2025, so building on that could be the best way to extend his career.
Photo courtesy of Benny Sieu, Imagn Images
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