If the Tigers are looking for a reasonably priced arm in free agency, David Peterson makes a lot of sense on paper. The left-hander, now 31, has the kind of profile that can quietly hold up a rotation: ground balls, limited damage on contact and enough recent improvement to suggest there’s still something left to tap into.
Peterson is one of only 15 left-handed starters who have thrown at least 400 innings over the last three seasons, and his underlying numbers help explain why he’s still in the conversation. He’s in the middle of that group with 23.7 batters faced per game, but he also ranks third in GB/FB rate at 2.01, one of just three pitchers above 2.00. On top of that, he owns the fourth-lowest Soft% at 14.1 and the fourth-lowest HR/9 at 0.67.
The issue has always been the walks. Peterson carries the highest walk rate in the group at 9.4 BB%.
But after he moved from the New York Mets to the Chicago Cubs in late June, that problem started to ease. His walk rate went from 4.04 to 3.82 in the second half, and that small shift opened the door for a much better stretch overall.
With fewer free passes and more strikeouts, Peterson was able to work with less stress in the count. After adjusting his four-seam fastball and sinker, he lifted his K-BB% from 8.6 to 13.9. That helped drive his xFIP down from 4.34 to 3.44 after the All-Star break, and he finished strong in Chicago.
The late-season turnaround showed up in other places too. Peterson improved from the 35th to the 54th percentile in limiting contact in the strike zone, and his Hard Hit% dropped from 46.2% to 37.2% after the move from the Mets to the Cubs. When his command is right, he still looks like a useful left-handed starter.
The financial side is where this gets especially interesting for Detroit. Peterson should not cost much, and a one-year deal around $13 million is presented as a realistic possibility. Projections point to a starter who can get beyond 140 innings with a 4.02 xFIP, which lines up closely with what he showed in Chicago, where he posted a 3.84 xFIP in 15 starts.
There are still real questions. Peterson’s pitch mix has been less stable over the last few seasons, with regressions in the Run Value of three of his main offerings: the sinker, curveball and changeup. From 2024 to 2025, he posted an average RV of 8.8 with those three pitches, but in his 23 outings in 2026 that number fell to -3.1, driven by inconsistency with the curveball (-4.6) and changeup (-5.5).
The slider, though, moved in the right direction once he got to Chicago. Its RV jumped from -7.7 in the stretch between 2024 and 2025 to 3.8. His four-seam fastball (3.5) and sinker (2.9) also added value.
For the Tigers, Peterson would fit into a pairing with Framber Valdez that isn’t built around missing bats at a high clip, but it would give them two left-handers who can generate weak contact, keep the ball on the ground and suppress home runs. That kind of profile could become even more valuable if Detroit’s defense takes a step forward next season.
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For a Tigers team that could use more certainty on the infield, Arraez makes obvious sense on paper. The catch is that he is headed into free agency with the expectation of a multi-year deal, which is where the market can get tricky fast. Philadelphia has been mentioned as a possible landing spot too, and that kind of competition is exactly why Detroit may like the fit without necessarily being able to control the outcome. [Read more 🡒]