Giants Pitcher Tyler Mahle Debuts Revamped Slider in Spring Training Win

Tyler Mahle made his first appearance in a Giants uniform Saturday afternoon, showcasing a significantly improved slider during a scoreless inning against the Athletics at Hohokam Stadium in Mesa, Arizona.

The right-hander, who signed a one-year, $10 million deal with San Francisco this offseason, struck out two batters while demonstrating notable improvements to his signature pitch. Mahle threw his slider six times during the outing, generating eight inches of glove-side movement compared to just 3.2 inches of horizontal movement in 2025, according to pitch tracking data.

“Last year, I had a cutter. It wasn’t a very good pitch but it had its purpose, which is a big part of it, too,” Mahle said. “But to get (the slider) to expand a little bit more glove-side is something I worked hard on.”

The enhanced slider produced immediate results. Three of the six sliders generated swing-and-misses, including one that struck out All-Star Jacob Wilson, while another landed for a called strike.

Giants catcher Eric Haase, who caught Mahle’s debut, praised the 31-year-old’s command and approach.

“I’d faced him a couple times in the past,” Haase said. “He had a noticeable step in his slider, if you want to put it that way. Where he was throwing the pitches today, the command was fantastic, even his misses. Everything you’d hope to see from him. If we can make that translate into 150 (innings) this year, I think he’s going to be in a great spot.”

Mahle’s pitch development reflects lessons learned from his 2023 Tommy John surgery. He previously experimented with a sweeper that generated 8.9 inches of horizontal movement, but the pitcher believes that pitch may have contributed to elbow discomfort because it required a different arm path. His current slider maintains a “hard curveball feel” that aligns with his natural delivery.

The veteran pitcher missed his first scheduled Cactus League start due to illness but appears on track with his spring preparation.

“I think there’s something to a guy like Mahle starting the game and having a calming influence,” said manager Tony Vitello. “It wasn’t a perfect inning, but just the approach.”

Haase also made headlines during the Giants’ 8-2 victory, launching a grand slam against Athletics pitcher Eduarniel Núñez. The blast marked the second consecutive day a Giants player hit a grand slam, following Victor Bericoto’s homer on Friday.

“Just trying to get something in the air, and for it to carry out of there is always a plus,” Haase said. “The approach was better and the timing was a lot better today.”

The 33-year-old catcher, who recorded two hits in the game, continues building his case for a roster spot despite Daniel Susac appearing favored as Patrick Bailey’s backup due to his Rule 5 Draft status. Haase brings significant experience to camp, having played 383 games over eight major league seasons.

“It doesn’t matter how many years you’ve played in the league. You get to where you don’t get immediate results or you don’t get a few strung together, you start pressing,” Vitello said. “Even in (batting practice) on the field, Haase was pressing on the field a little bit. But I think his determination kind of suppressed that. He just came out here and played ball.”

Right-hander Trevor McDonald also impressed in his bid for the Opening Day roster, throwing two perfect innings with three strikeouts. His sinker averaged 93.4 mph, slightly down from his 95.2 mph velocity in his first Cactus League appearance, but he effectively commanded both his sinker and slider while generating four whiffs.

“When these come out of the ‘pen and they’re just filling up the zone, they’re very nasty, hard to hit,” Haase said of McDonald’s performance.