What Can the Cubs Reasonably Expect from Jameson Taillon in 2025?

[Matthew Trueblood]

It was fun to watch the veteran righthander rebound from a tough 2023 and put up a strong second season for the Cubs last year. Under the hood, though, lie enough orange flags to force us into asking some questions.

Image courtesy of © Chet Strange-Imagn Images

By the relatively low standards of this moment in baseball history, Jameson Taillon is a workhorse. He takes the ball, weathers early trouble when it comes, and usually gets fairly deep into games. He's been consistently available to the Cubs over his first two seasons of a four-year deal, even though he missed the start of 2024 with a back problem and a fortnight in 2023 with a groin strain. He's been eager to get back on the mound, good at staying there, and creative and smart in his approach.

Last year, that paid off big-time on the top line of his stat page, as he reduced his ERA from 4.84 in 2023 to 3.27. Sixteen of his 28 outings were quality starts, and in addition to his 12 credited wins, he left in a position to get the win four times, only to see the bullpen squander the advantage. Taillon was, almost inarguably, a much better pitcher in 2024.

Alas, we have to say "almost," because there are also some worrying trends of which to take note. Taillon's velocity fell off significantly, by more than a mile per hour on average, perhaps because he worked so hard to get back to the active roster after his spring training back trouble.

Largely as a result of that loss of zip, Taillon also missed many fewer bats in 2024. His per-pitch and per-swing whiff rates sagged noticeably, depressing his strikeout rate to 18.4%. Over the three campaigns before that, he'd had a much more sustainable 21.7% punchout rate. Opponents' average exit velocity ticked up, even as Taillon (with the help, perhaps, of Wrigley Field and its extremely pitcher-friendly summer) allowed six fewer homers and reduced opponents' slugging average by .055. That might imply that he got somewhat lucky, based on environment and on more batted balls creating less trouble. Worse, Taillon's velocity only plunged deeper late in the season, dipping below 92 miles per hour in August and September, so it's not as though he showed signs of having shaken off the back injury and recovered his ability to dominate.

On the other hand, Taillon did fill up the zone much more consistently in 2024, which is a part of the story around his lack of whiffs. The 54% of his pitches categorized by Statcast as being in the strike zone was easily a career-best mark, and while being in the zone that much can lead to more contact, it also means more strikes. Taillon pulled his walk rate back down to 4.9% last year, thanks to pounding the zone more confidently. If the weather patterns change in 2025, maybe he can simply revert to a bit of nibbling and try to get hitters to chase more bad balls.

Taillon also changed up his pitch mix a bit, with beneficial effects. Against righties, he leaned hard into a sweeper-cutter combination, forcing batters to distinguish often between two pitches with very different shapes but which tended to start on similar trajectories.

Against lefties, meanwhile, a small uptick in usage for four different pitches allowed Taillon to throw many fewer fastballs, which was a boon for him; his fastball tends to get hit hard by opposite-handed batters.

This tweak to the arsenal was effective, because for righties, the cutter and sweeper have an unusual amount of spin mirroring. With two pitches that move partially in the same direction but end up with very different shapes, the hitter usually has a major difference in spin axis to try to pick out when seeing the ball out of the pitcher's hand. With Taillon, though, the cutter and sweeper both seem like they'll maintain largely vertical trajectories—only to be drastically affected by seam-shifted wake effects and take off to the arm side. In the visual below, the distributions on the left show each of Taillon's pitches' expected movement based on their spin axes. On the right are the actual movement distributions for the pitches. You can see how both the cutter and the sweeper veer left, relative to what their spin profiles imply.

Lefties run into a different version of the problem, but an equally real one. With fewer fastballs coming in, the spin mirroring of Taillon's four-seamer and his curve becomes more potent at fooling hitters. Small things like these make hitters swing a little less often and a little more tentatively, and can help a pitcher make up for diminished stuff. On the strength of his more varied repertoire, Taillon went from 55th in the percentage of all pitches that became called strikes in 2023 (16.9%) to 21st last year (18.2%). Indeed, the Cubs were good at finding called strikes, overall, with Javier Assad (7th) and Kyle Hendricks (16th) ahead of Taillon on a list of 141 pitchers. The team replaces Hendricks with Colin Rea this year; Rea was 19th on that same list.

More called strikes are good, and craftsmanlike pitch combinations are good. Taillon keeps finding ways to succeed, so far, and he's only 33 years old, so there's no reason he ought to break down or steeply decline in 2025. Yet, Cubs fans have to slightly temper their expectations for him. If he remains unable to miss bats at anything even approximating an average rate, Taillon's results will probably regress this year, so his success last season (although earned and impressive) feels fragile as spring training begins.

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