While the San Francisco Giants have generally upgraded their offense in recent seasons, the starting pitching is a significant question heading into 2026. How far the team goes will depend on their starting rotation. Namely, how well will the pitchers in the back end of the rotation produce?
To that end, Tyler Mahle is working on a change to his approach during spring training. It was on display on Saturday, Feb. 28, when Mahle made his spring training debut against the Athletics.
In one inning of work, Mahle showed off an improved slider several times, with effective results.
The San Francisco Giants’ Tyler Mahle’s Slider had Significantly More Movement
A slider isn’t a new pitch for Mahle. But the slider he threw against the A’s was a lot different than the one he threw for the Texas Rangers in 2025.
Justice delos Santos of the Bay Area News Group detailed the differences in Mahle’s slider.
“While facing the A’s, Mahle generated eight inches of glove-side movement,” delos Santos wrote. “In 2025, by contrast, Mahle only generated 3.2 inches of horizontal movement with his slider. So far, the returns have been encouraging. Three of the six sliders that he threw generated a swing-and-miss (one striking out All-Star Jacob Wilson) while another landed for a called strike.”
Normally, it’s not wise to take too much from one start, especially in spring training. That said, that kind of skepticism is usually reserved for reading too much into a player’s results. A pitch moving significantly more than it did the year before is a different story. That’s not the kind of thing that will simply be evened out by a bigger sample size.
An Improved Slider Should Curb Regression Concerns
Mahle’s 2025 was limited to just 86.2 innings over 16 starts. That said, when he was out there, he was an effective pitcher for the Rangers a season ago. Mahle finished 2025 with a 2.18 ERA, 1.131 WHIP, a 1.9 fWAR and a 2.2 bWAR. If the Giants can get that kind of production from Mahle over roughly 150-175 innings and 30 starts in 2026, they’d certainly take it.
That said, Mahle’s projections suggest that regression might be coming.
Baseball Reference projects Mahle to post a 3.26 ERA and 1.219 WHIP while Fangraphs projects Mahle at a 4.05 ERA and 1.29 WHIP.
Part of the problem for Mahle is that while he was once a strikeout pitcher, that’s changed in recent seasons. Mahle posted a K/9 rate of 7.1 in 2024 and had an even more modest 6.9 K/9 in 2025. The more your pitches find bats, the more likely they are to find holes in the defense for base hits.
But if he’s throwing a slider with more than twice the movement that he had a season ago? That will go a long way in making more bats miss. And with a new (or, at least, improved) pitch, it will also be harder for hitters to make loud contact on him. More pitches mean less predictability.
Obviously, Mahle has a long way to go to prove that his slider can be consistently effective. But the start against the Athletics is a big first step.
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