Tigers Starter Casey Mize's Splitter is Fueling His Biggest Breakout Yet

The former Detroit Tigers first round pick is looking like his best self.

Apr 17, 2026; Boston, Massachusetts, USA; Detroit Tigers starting pitcher Casey Mize (12) delivers a pitch during the first inning against the Boston Red Sox at Fenway Park. | Paul Rutherford-Imagn Images

The Detroit Tigers came into the 2026 seasons with arguably the most formidable one-two rotation punch in the game. With reigning back-to-back Cy Young award winner Tarik Skubal and All-Star Framber Valdez at the top of their staff, they hoped the two lefties could take them on their deepest playoff run.

After the two, though, there were some question marks. After a great half season in 2024, Jack Flaherty returned to Detroit in 2025, but struggled with a 4.64 ERA. The young right-hander, Keider Montero, was close to league average last season, but bounced between the rotation and bullpen.

Jackson Jobe was injured to start the season, so the clear number three coming in was Casey Mize. The right-hander had a career year in 2025, making his first All-Star team, but it came apart in the second half.

The former number one overall pick is looking as good as he ever has in his major league career to begin his sixth season. MLB.com's Jason Beck attributes a big part of that to his splitter being back to the form that made him such a highly coveted prospect.

Mize's Splitter Has Been Untouchable

Detroit Tigers pitcher Casey Mize. | Jesse Johnson-Imagn Images

Coming into the season, Mize's splitter was a pitch that he relied on pretty heavily, even if it wasn't the wipeout pitch it once was. Of his five pitches in 2025, the splitter was his second most used pitch at 24.2 percent of the time, according to Baseball Savant.

Despite its high usage, it was the pitch that hitters did the most damage against. Opposing hitters hit .297 with a .494 slugging percentage against Mize's splitter last year, both of those were the highest numbers against any pitch he threw.

It was still getting whiffs at a 33.2 percent rate, but hitters were still seeing it well. According to Baseball Savant, it had a -11 run value on the season.

That has changed so far in the 2026 campaign. Beck described the pitch as "looking as good as it has since he left Auburn and turned pro," back in 2018. The numbers back that up, too.

Through four starts, Mize has a 2.78 ERA in 22.2 innings. What's most encouraging, though, are his strikeout numbers. His current 9.9 K/9 would be the highest of his career and is a better mark than what he had in the first half of 2025 when he was an All-Star. His splitter is a big reason for that.

It's again his second most used pitch at 29.9 percent, but opposing hitters are having a much harder time with it this time around. The whiff rate on the pitch is up to 35.7 percent and hitters are batting .138 with a .172 slugging percentage against the pitch.

Not only that, but the run value is at three so far this year, a significant change over the last season.

With the pitch that made him so highly touted looking like it did when he was drafted, Mize might be in for his best career year yet. In 28 starts last year, he collected 1.4 bWAR. So far this year, he's up to 0.8. If Mize continues this dominance, the Tigers could pitch their way back into the postseason.