The latest and greatest iteration of Casey Mize (his journey isn’t complete yet)

While Sweeper is the focus, so is improving existing parts of his tonal mix.

Mize knew his four-seam fastball was losing its carryability, and that was something he wanted to try to fix. He also knew it was the hardest pitch to change.

“We literally just flipped the seam on the ball to try to get more induced vertical break,” Kress said. “It’s really another seam direction trick to try to generate more carries. We saw this last season with Luke Weaver, where the Yankees changed the seam direction of Luke Weaver’s fastball and made a huge jump. That’s because he had a really weird grip on his fastball, which was unusual.”

This season, Mize has gained an inch of vertical movement on his fastball, albeit with a slight decrease in velocity. This is not a major change, but more of an incremental improvement.

Miz is also curious what Kress will say about his splitter.

His signature swing-and-miss pitching at Auburn didn’t make him an elite player in professional baseball.

“I was like ‘OK, what’s going to happen with my split?'” Miz recalled.

Initially, the advice was to bowl at a faster pace. But midway through the season, with mixed results, Kress proposed another change: more cuts and more top spins on the court.

Kress learned from the changeup that differentiating its vertical movement from a pitcher’s primary product is key.

“When you take away the vertical break, it moves away from the four-seam cloud or the four-seam motion profile, and that’s the driver of more swings and misses,” Kress said. “As far as he’s concerned, when he’s able to push the ball down to zero line, zero vertical line, it works really well.”

From the looks of it, his splitters have taken a step back this year.

His run value on the spreader (-1.96 wFS per 100 pitches) suggests he should throw the ball less often, rather than more often than he did in 2025, especially later in the season.

But Mize explains why evaluating independent pitch values ​​can be problematic.

“I gave up a home run on the pitch, which can negatively impact the value of any type of pitch, which sometimes happens if I leave (the splitter) in the zone,” Mize said. “But I threw 28 (run balls) in one particular game and I got eight swings and misses. The run value went down because of the damage that happened with home runs and doubles. I understand how they calculated it, but if you look at it and say ‘Oh, your run value was bad, you need to scrap that pitch,’ like, I’d be worse off without that pitch. I need to throw that pitch.”

For example, while his splitter’s run value dropped, his fastball earned a slight positive run value for the first time in his rookie year in 2020. This speaks to the power of a wider pitching selection.

“I think the bigger thing is probably we’re adding more throws … allowing us to not have to rely on throwing as many four-seamers to make it work better,” Kress said.

Mize finished the season as a five-seamer, missing a pitch more than 34 percent of the time, while hitting at least 12 percent of his four-seamers. In 2024, he threw just three pitches in double digits.

While most of Mize’s production doesn’t rank as knockout, the expanded tonal mix improves his overall game.

And 2025 is just a chapter. Mize and Kress will be curious to see how his pitching mix fares with another offseason of improvement.

Miz’s story is one that keeps repeating itself.

It also shows how the coaching staff inside and outside affiliated baseball can work together harmoniously.

For example, Mize believes the Tigers have a good pitching coach. They also have access to Hawkeye data that no one outside of affiliated baseball likes.

“They’ve done a really good job of reviewing the Hawkeye data and understanding how I’m moving, trying to stay ahead of some of the mechanical stuff that can bleed every now and then,” Mize said. “We’ve been able to correct some things before they get too bad for trends, which has been really beneficial this year. ‘Hey, you’re starting to counter-spin too much,’ or, ‘You’re flying.'”

But he also wants to get out and get other opinions on how to optimize his arsenal and where he can improve. The Tigers approved his plan.

“Combining all those things together allowed me to take a step forward this year,” Mize said.

And this year is just one chapter. The story of Mize’s development is incomplete. This is a journey that will continue in the offseason, with another breakout, another performance leap, well within the realm of possibility.