The Minnesota Twins made their first foray into free agency, signing right-handed reliever Grant Hartwig to a minor-league deal last week with an invitation to spring training. They have assigned him to the St. Paul Saints roster.
It’s not a major-league deal that will have an immediate impact on their roster. Still, Hartwig offers little more intrigue than a typical minor-league signing. Given how depleted the Twins’ bullpen is, any pitcher they sign to a minor league deal with any major league service time, such as Hartwig, will be a viable candidate to try to crack a spot in their bullpen next year.
So just who is Grant Hartwig?
Hartwig was an undrafted free agent whom the New York Mets signed in 2021 after completing his final season with Miami University in Ohio. He rose quickly through their farm system in 2022, pitching at each level of A-affiliated ball. Hartwig had a combined 1.75 ERA in 39 relief appearances at the four levels with a 1.09 WHIP, 10.3% walk rate, and 35.5% strikeout rate.
His dominant Triple-A performance in 2022 didn’t carry over into his first season in the majors, when he debuted June 19, 2023. Hartwig made 28 appearances with the Mets in 2023, pitching to a 4.84 ERA, 9.5% walk rate, 19% strikeout rate, and 1.38 WHIP in 35 ⅓ innings.
Hartwig pitched in only four games with the Mets in 2024, and knee surgery in mid-June that year limited him to only 33 minor-league games. All four of his major-league appearances came before his knee surgery, and he had a 6.75 ERA with four walks allowed and four strikeouts in 6 ⅓ innings. At Triple-A, Hartwig had a 4.68 ERA, 22.4% strikeout rate, and 11.5% walk rate in 42 ⅓ innings.
Last year, he rebounded from his lousy 2024 season, but didn’t appear in the majors. He pitched in 21 games and posted a 3.42 ERA, 1.56 WHIP, 8.8% walk rate, and 29.2% strikeout rate in 23 ⅔ innings. However, Hartwig didn’t finish the 2025 season in the minors. The Mets released Hartwig so he could sign with the Hanshin Tigers of the Japan Central League.
While pitching in Japan, Hartwig continued his success with Triple-A Syracuse, posting a 3.65 ERA, 1.29 WHIP, 15.1% strikeout rate, and 13.2% walk rate in 12 ⅓ innings across 16 appearances. Even with a high walk rate in the short sample size in Japan, the Twins liked what they saw from him stateside and abroad and took a flyer on him as a bullpen option with the Twins and Saints next season.
Even as a reliever, Hartwig still uses four pitches in addition to his fastball: a sinker, sweeper, cutter, and changeup. Hartwig used the sinker most often during his limited time in the majors, but his sweeper proved the most effective against major league hitters.
In 2023, he threw it 201 times, and hitters had a .147 batting average against it in 38 plate appearances. In 2024, Hartwig threw it only 39 times in seven plate appearances and kept opposing batters to just one hit off it.
With Hartwig’s track record of success in the high minors, experience pitching overseas, and service time in the majors, he’s the type of pitcher that the Twins have always had an interest in bringing in on a minor league deal each off-season. Last year, he showed what he could do with a healthy knee, and his sweeper complements what he can do against hitters when he’s up in counts against them.
Hartwig may have limited opportunities with the Twins this upcoming season, and he could only make sporadic appearances, like he did in 2024. But given the depleted state of Minnesota’s bullpen, it could give a pitcher like him, who’s accumulated 32 games in the majors, the chance for a bigger opportunity in 2026.
However, Hartwig would have to pitch well enough in spring training first to prove that. Even if he doesn’t make the Opening Day roster, he’d need to maintain his success with the Saints to be one of Minnesota’s first men up in any situation. Until the Twins pursue some relievers with more major-league experience, fans will need to become familiar with relievers like Hartwig, because they may have a role in the Twins’ bullpen in 2026.
