Fantasy Baseball Starting Pitcher Arsenal Changes (Week 24): Pitch Mix, Velocity, and Movement

September 5, 2024

Corbin Young examines two fantasy baseball pitcher risers and sleepers displaying changes in their pitch mix, movement, and velocity heading into Week 24 (2024).

Welcome back, RotoBallers, to my weekly "Starting Pitcher Arsenal Changes" article series for Week 24 of the 2024 fantasy baseball season. Today's article will discuss Shota Imanaga and Hunter Greene. For those new to this column, each week, we cover a few starting pitchers and their arsenal changes via pitch mix, velocity, and movement.

We're at a point where the pitch movement, arsenal, and velocity should tell us a story with several starts under their belts. With more injuries likely coming soon, we'll want to continue identifying streaming pitcher skills or struggling pitchers with underlying metrics suggesting better results coming soon. We have about a month left in the fantasy baseball season, causing fantasy managers to make crucial decisions for the final stretch.

Pitchers can make notable changes in smaller samples, so let's see if we can find something with these two starting pitchers finding success and understand why. Let's look through my process of examining starting pitchers and their arsenals. Reach out to me on X if you have a pitcher you have questions about who may be included in a future article.

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Regression Hit Shota Imanaga, But He Settled Down

Imanaga had a 3.07 ERA, 1.11 WHIP, 24 percent strikeout rate, and 4 percent walk rate in the first half. His 4.05 xERA in the first half suggested regression, and we saw that in June (5.67 ERA, 1.33 WHIP, 4.56 xERA). Imanaga settled down in the second half, with a 3.23 ERA, 0.98 WHIP, and 3.62 xERA.

Pitch mix-wise, we saw a slight fluctuation monthly, but it remained steady from the first to the second half. Imanaga relied on his four-seam (54.8 percent) and splitter (30.8 percent), with the sweeper (6.7 percent) rounding out his arsenal in the first half.

He lowered his four-seam by four percentage points (50.6 percent), with the splitter staying the same (29.6 percent) and slightly more sweepers (9.1 percent). Imanaga has a consistent attack against right-handed hitters, with 53.8 percent four-seamers and 34.8 percent splitters.

Instead of being a two-pitch pitcher against left-handed hitters, Imanaga uses the sweeper more often at 31.3 percent while trading it for fewer splitters (13.6 percent). Let's look deeper at Imanaga's arsenal because there might be potential red flags.

Hitters Have Been Crushing Imanaga's Four-Seam

Imanaga's four-seam allowed a .227 wOBA (.301 xwOBA) through May. However, hitters have been crushing it since June 1. That's evident by the four-seamer allowing a .371 wOBA (.338 xwOBA). It makes us wonder if he lost velocity or the pitch shape changed.

Imanaga posted elite levels of induced vertical break (IVB) on the four-seam at 18.8 inches through May, with 9.9 inches of arm-side run and a 12.3 percent swinging strike rate. From June 1, Imanaga's four-seam IVB fell nearly an inch (17.9), with one-half inch more horizontal movement (10.4). Unsurprisingly, Imanaga's four-seam swinging strike rate plummeted over five percentage points to 7.8 percent since June 1.

We'll note that Imanaga's IVB since June 1 still qualifies as above average. That means it's possibly related to location or natural regression with the batted ball results and swinging strike rate decline.

Imanaga's release points and extension hadn't changed, but we saw him pepper the upper third of the zone. He threw 56.2 percent of his four-seamers in the upper third of the zone from March to May. That's close to the four-seamers he threw in the upper third at 54.3 percent from June 1 and beyond.

Hitters might be adjusting to Imanaga's approach of throwing more than half of his four-seamers in the upper third of the zone. We're speculating since the batted ball results regressed based on the expected stats and the four-seam continues to lose whiffs. That's concerning because Imanaga's four-seam theoretically should generate whiffs up in the zone, with the elite IVB.

Imanaga's four-seam comes at a flat vertical approach angle (VAA) at -4.1 degrees, which falls into the above-average range through May, slightly changing to -4.2 degrees from June 1. Since it's not a significant change in VAA, it seems like a mixture of regression on the four-seam away from his favor and hitters looking to attack the heater in the upper third.

Imanaga is Throwing More Splitters

Imanaga relied on the splitter often, peaking in May (37.1 percent), dipping to a season-long low in July (24.8 percent), and bumping back to 30.6 percent in August. Imanaga's splitter has been a consistent and reliable offering throughout the season, and better in July (.186 wOBA) and August (.225 wOBA) compared to a season-long wOBA of .246.

With hitters crushing the four-seamer over the past few months, he needs the splitter to continue eliciting whiffs. Through May, Imanaga's splitter generated a 26.7 percent swinging strike rate, identical to his swinging strike rate from June 1 at 26.7 percent.

He consistently locates the splitter below the zone, causing hitters to chase. In the first few months, Imanaga threw his splitter below the zone over 57 percent of the time, translating to a .220 wOBA (.200 xwOBA) and a 29 percent swinging strike rate.

From June 1 and beyond, Imanaga's splitter was thrown below the zone over 48 percent of the time. Interestingly, Imanaga hasn't been throwing the splitter as much below the zone, though we know it can be a tough pitch to command for some. Regardless of the location change, his splitter is nearly unhittable, with a .174 wOBA (.218 xwOBA) and a 29.5 percent swinging strike rate.

Summary

Though we didn't examine Imanaga's sweeper, he possesses at least one effective pitch against either side of the plate. The sweeper allows a .240 wOBA (.219 xwOBA), with a splitter resulting in a .214 wOBA (.236 xwOBA) versus lefties.

Meanwhile, Imanaga's splitter is the lone pitch that dominates right-handed hitters, with a .249 wOBA (.255 xwOBA). He possesses near-elite control, evidenced by a 31.3 percent ball rate while boasting a high-end swinging strike rate (14.6 percent).

It might make sense for Imanaga to lower his four-seam usage, though it's still an above-average pitch in IVB and VAA that he peppers in the upper third. Fortunately, Imanaga's splitter is deadly, with the sweeper being a weapon against same-handed hitters.

As we close out on 2024, we'll want to invest in Imanaga in 2025 because we could envision another step forward for him next year.

Hunter Greene's Four-Seam Changed

Greene's four-seam hardly wowed us throughout his career, with a gradual decline from a swinging strike rate of 13.2 percent (2022) to 11.3 percent (2023) and a 10.7 percent (2024). However, it's worth highlighting the four-seamer movement profile.

Greene's four-seam had a slight improvement in IVB (16.6 inches), yet it lost over two inches of arm-side movement. That's interesting because his VAA didn't change, with -4.6 degrees across the past few seasons.

Greene's horizontal release point shifted by nearly five inches (4.92), causing fewer inches of arm-side movement compared to 2023. That suggests Greene's horizontal release point moved closer to the midline of his body, leading to pitch shape changes on the heater.

We've seen an improvement in Greene's four-seam located in shadow and chase areas of the zone. He threw his four-seam in the chase and shadow zones 65.7 percent of the time, translating to a .244 wOBA (.250 xwOBA). Greene's four-seam performed worse in 2023 (.336 wOBA) and 2022 (.367 wOBA) with slight fluctuations, evidenced by 70 percent in the chase and shadow areas in 2023 compared to 65 percent in 2022.

That slight release point adjustment, leading to a movement profile change, seems to have ensued in the results against Greene's four-seam improvement. That's especially notable in the heart and shadow areas of the zone in 2024 compared to the previous two seasons.

Greene's New Splitter

After primarily relying on the four-seam and slider, Greene added a splitter in 2024. Greene's splitter usage peaked at 13.4 percent in June, with the other month above 10 percent, including August (10.8 percent). It's been a mixed bag of results, with the splitter usage increase not aligning with better outcomes.

Greene mainly throws the splitter against left-handed hitters, allowing a .297 wOBA on the season. His splitter had the best outcomes in June, with a .110 wOBA (.200 xwOBA) and a .000 wOBA (.000 xwOBA) in August. He needed a third pitch to mix in against opposite-handed hitters, but he struggles to generate whiffs, evidenced by a season-long 11.2 percent swinging strike rate.

We've been yearning for Greene to find a third pitch that might be helpful against righties and overall. Unfortunately, Greene's splitter doesn't elicit whiffs like the slider, but it might be something that he continues to work on in 2025.

As mainly a two-pitch pitcher, Greene toyed with a changeup in the past, which he mixed in about 5 percent of the time. He introduced a splitter and slowly ramped up the usage, with ups and downs. Greene's splitter hasn't been effective from a whiff standpoint, evidenced by the 11.2 percent swinging strike rate.

The splitter has been decent against left-handed hitters, with a .297 wOBA, though the xwOBA (.219) suggests better results since it allows weak contact. Greene's improved four-seam, consistent slider, and splitter lead to a more effective approach to left-handed hitters compared to the past where there was only one decent offering.

The visual below shows a more detailed zone chart, with the dotted line signifying the fine line between the shadow and chase areas.

Though Greene locates the splitter outside the zone with a 38 percent zone rate, it doesn't generate chases, evidenced by a brutal 23.6 percent chase rate. When Greene throws the splitter in the chase areas, it allows a .345 wOBA and a 13.7 percent swinging strike rate.

However, the splitter was most effective when he located it in the shadow areas, resulting in a .225 wOBA and a 17.9 percent swinging strike rate. Since we're still dealing with a small sample of splitters, it's hard to be confident in how he'll use the pitch moving forward. Regardless, he needs another pitch like the splitter to help against opposite-handed hitters, and potentially elicit whiffs.

Summary

Greene's four-seam has been performing better against right- and left-handed hitters. That's possibly due to the release point and movement profile changes or him commanding the heater better.

The splitter is interesting, but we haven't seen consistent and positive outcomes yet. Theoretically, Greene's splitter could elicit more whiffs, especially if they're located in the shadow areas more often, causing hitters to chase more often.

The xERA (3.82) being nearly one run higher than his actual suggests luck in his favor, especially with a similar level of skills via swinging strike rate. Unfortunately, Greene landed on the injured list with an elbow injury in mid-August, so there's a low chance of him finishing the season strong.

There have been enough small tweaks to Greene's arsenal to cause us to buy into him in 2025, assuming the elbow issue isn't serious.

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