Starting Pitcher Arsenal Changes - Pitch Mix Analysis for Fantasy Baseball (Week 12)

Corbin's starting pitcher fantasy baseball sleepers, breakouts and risers for Week 12 of 2025 displaying changes in their pitch mix, movement, and velocity.

Welcome back, RotoBallers, to my weekly "Starting Pitcher Arsenal Changes" article series for Week 12 of the 2025 fantasy baseball season. We researched 30 starting pitchers so far, with three more in this column, including two surgers and one faller. Today's article will discuss a few starting pitchers who made actionable adjustments, like a release point change or a new pitch, location changes, and whether they matter moving forward.

For those new to this column, we cover a few starting pitchers and their arsenal changes via pitch mix, velocity, and movement each week. Since it's early, we're looking for new pitches, velocity, and movement changes. When we find significant release point shifts, it can potentially impact their movement profiles in 2025.

Pitchers can make notable changes in smaller samples, so let's see if we can find something with these starting pitchers. Statcast provides so much data to digest and compare quickly to past seasons. Let's look through my process of examining starting pitchers and their arsenals. Reach out to me on X if you have a pitcher and have questions about it. Thank you for reading!

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Yoshinobu Yamamoto's Horizontal Release Point Change

Yamamoto shifted his horizontal release point by over seven inches in 2025 while maintaining his vertical release. That led to Yamamoto's lower arm angle (two to three degrees below), theoretically leading to potential movement profile changes. Yamamoto's cutter and splitter added vertical movement compared to his rookie season.

With Yamamoto's arm angle moving farther away from his midline, one would expect the horizontal movement profiles to change. We've seen his splitter fade two more inches toward his arm side. Meanwhile, Yamamoto's cutter is cutting one to two inches more toward his glove side in 2025.

The cutter is noisy and something he hardly uses, having used only 65 combined over the past two seasons. Let's review the splitter since it's fading toward his arm side more. That suggests his splitter is moving down and inside toward right-handed hitters.

Yamamoto's Effective Splitter Against Right- and Left-Handed Hitters

The splitter has been effective against both sides of the plate for Yamamoto. We've seen that trend continue after his rookie season into 2025. Yamamoto's splitter has been better against right-handed hitters, allowing a .176 wOBA (.193 xwOBA). That's notably better than his 2024 outcomes versus righties (.308 wOBA, .258 xwOBA).

The splitter remains his best pitch versus lefties, evidenced by a .174 wOBA (.197 xwOBA), with the four-seam close behind, allowing a .214 wOBA (.263 xwOBA) among his pitches thrown over 10 percent of the time.

Yamamoto's cutter has been sneaky good against left-handed hitters over the past two seasons, allowing a .173 wOBA (.206 xwOBA) in 2025. However, Yamamoto sparingly used the cutter, around seven to nine percent of the time against lefties over the past two seasons.

Yamamoto is Throwing More Sinkers and Cutters to RHH

Speaking of Yamamoto's cutter, he increased his usage to right-handed hitters to 10.6 percent from a low 3.2 percent in 2024. Unfortunately, Yamamoto's cutter results have been awful, with a .559 wOBA (.581 xwOBA) against righties. He seems to throw his cutter as a harder version of his slider, almost gyro-like, which he locates low and away from right-handed hitters.

Yamamoto located the cutter low and away from right-handed hitters over 33 percent of the time in 2024. However, Yamamoto's cutter locations spiked to 55 percent in areas low and away from righties in 2025. It's a small sample as one of the least-used pitches, but hitters crush the cutter when thrown in the zone.

When Yamamoto leaves the cutter in the zone and doesn't precisely locate it low and away, hitters have been destroying the pitch, with a .859 wOBA (.775 xwOBA) in 2025. That's worse than his 2024 cutter results in the zone. Yamamoto tries to use the cutter to steal strikes when behind in the count, throwing it 18.6 percent of the time against right-handed hitters in those situations. He might want to shift to the curveball more often instead, since it allows a .228 wOBA (.256 xwOBA) when behind in the count.

Yamamoto has also been throwing his sinker more against right-handed hitters, with a usage rate of 12.4 percent in 2025, up from 5.4 percent (2024). He tries to use the sinker as a fastball that fades low and inside to right-handed hitters, where he threw it 41.5 percent of the time (2024), increasing to 54.1 percent (2025).

Interestingly, Yamamoto's sinker was nearly unhittable low and inside in 2024. However, those numbers regressed in 2025, yet are still decent. As we noted earlier with the cutter, Yamamoto seems to try to steal strikes via the sinker when behind in the count against right-handed hitters.

Yamamoto has a deep arsenal against both sides of the plate, with interesting usage changes via the cutter and sinker that serve a purpose beyond generating whiffs.

Summary

Admittedly, I was wrong about having Yamamoto as an NL Starting Pitcher Bust, with the main concern being the lengthy injury. There was no denying Yamamoto's skills, evidenced by a 20 percent strikeout minus walk rate and an above-average swinging strike rate of 12.9 percent. The arm angle and release point changes might be fluky, or they might help him stay healthy with a different arm slot.

Ranger Suarez is Throwing More Changeups to RHH

Suárez's changeup has been his best pitch for whiffs, with a 19 percent swinging strike rate in 2025, slightly higher than his career average (16.8 percent SwK). He has been using his best pitch more often against right-handed hitters, throwing it 24.2 percent of the time, up from 15.7 percent (2024).

Besides the whiffs, the batted ball results have been solid. That's evident by Suárez's changeup allowing a .264 wOBA (.271 xwOBA) against right-handed hitters in 2025, similar to or slightly better than in 2024. Has anything changed with Suárez's changeup? We've noticed Suárez's changeup added five to eight inches of downward movement in 2024 and 2025 compared to the previous two seasons.

His changeup was gradually slower throughout his career, with a two mph drop over the past two seasons compared to 2023. Besides the velocity drop, Suárez's changeup spin rate fell to a career-low spin rate.

Suárez traded more changeups for fewer four-seamers and curveballs against right-handed hitters. For context, Suárez's changeup spin rate of around 1,300 RPM would be slightly higher than Shota Imanaga's splitter.

Typically, split fingers hover around 1,100 to 1,200 RPM, making it a volatile pitch that can generate whiffs when located well. That could suggest that hitters struggle with Suárez's changeup with a movement profile that's significantly different than just a few seasons ago.  

Suárez is Throwing Fewer Sinkers to Left-Handed Hitters

Typically, Suárez tossed sinkers to left-handed hitters 64-65 percent of the time from 2021 to 2023. However, he lowered the sinker usage to 52.7 percent in 2024, down to 43.8 percent in 2025 against left-handed hitters. For context, opposing offenses tend to stack righties against Suárez, so we're dealing with a smaller sample.

Suárez's sinker has been effective against left-handed hitters, as a pitch he typically throws toward the inside corner, leading to weak contact. That's evident in Suárez's sinker allowing a .147 wOBA (.236 xwOBA) in 2025 versus lefties. However, the batted ball results against the sinker fluctuated over the past few seasons.

Suárez's sinker locations have been relatively similar when comparing 2024 and 2025. However, the batted ball results improved against left-handed hitters via the sinker. That could indicate Suárez's sinker outcomes might be slightly fluky in the early 2025 sample, or the sinker is performing as expected this season.

When something goes down, another thing rises. That's the case with Suárez throwing fewer sinkers against left-handed hitters in favor of more sliders. It's worth highlighting that Suárez's slider usage is the highest since 2022 (10.5 percent) against left-handed hitters. However, Suárez has thrown 21 sliders overall in 2025, so it's a moot point.

Summary

Suárez has been outperforming his xERA (3.44) because he doesn't have above-average strikeout skills. He continues to generate groundballs (53 percent) via the sinker (82 percent) and changeup (53 percent), though his 9.4 percent SwK doesn't pop. The luck factors, specifically his hit rate (29 percent) and home run rate (five percent HR/F), have favored him. Suárez eats innings when healthy, with his most notable arsenal change being the changeup's additional downward movement and lower spin rate.

Yusei Kikuchi's Lower Arm Angle

Kikuchi has a lower arm angle in 2025 (33.5 degrees). It's a career low, being eight degrees lower than in 2024 (41.9) and 2023 (42). That's a significant change in his arm angle, which should impact his pitch movement profiles.

Kikuchi has a lower vertical release point (1-1.5 inches lower) and a horizontal release over two inches farther away from his midline. That indicates Kikuchi is using a more three-quarters arm slot after having a more over-the-top approach. The horizontal release point is the most notable because we've seen a gradual decline in Kikuchi's vertical release.

Kikuchi's new arm angle coincided with more downward movement and a slight increase in his horizontal pitch movement across his overall arsenal. Most notably, his four-seam and changeup added arm-side fade. Meanwhile, his changeup was the only pitch to gain downward movement with the new arm angle.

Kikuchi's New Changeup

Kikuchi has a newer changeup, with additional downward movement and fading more often. His vertical and horizontal movement via the changeup would be career highs. So what changed? Kikuchi's changeup velocity dropped by one mph in 2025 compared to 2024, but it's two to three mph lower than in 2022 and 2023.

The changeup's spin rate fluctuated throughout his career, and it's the lowest since 2021. It's hard to compare to four seasons ago, but Kikuchi's changeup elicited a career-best 20.8 percent swinging strike rate in 2021. However, Kikuchi's changeup swinging strike rate in 2025 sits at 11 percent, his best among his arsenal.

Besides the drop in whiffs, Kikuchi's changeup performed as one of his best pitches against right-handed hitters. That's evident in Kikuchi's changeup allowing a .248 wOBA (.297 xwOBA) against righties in 2025 versus a .200 wOBA (.220 xwOBA) in 2024 and a .216 wOBA (.240 xwOBA) in his career.

The changeup locations have been part of the issue since he threw it 28.1 percent in the area low and away from right-handed hitters in 2025, leading to a .059 wOBA. Meanwhile, Kikuchi located the changeup in that area 44 percent of the 44 percent in 2024, resulting in a similar .061 wOBA versus righties.

If Kikuchi can better locate the changeup, maybe we'll see the whiffs return. However, Kikuchi's changeup still generates weak contact.

Summary

Kikuchi typically struggled with control, with a 37 percent ball rate in 2025, similar to his career average (36 percent). The whiffs were the difference maker, with high-end swinging strike rates throughout his career, yet a career low in 2025 (nine percent). We didn't cover Kikuchi's slider since that's another key to his success in previous years. Like the changeup, Kikuchi's slider isn't eliciting whiffs (9.1 percent SwK), and he might be leaving it in the zone too often. He needs the slider and changeup whiffs, or we'll want to stay away.

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