Starting Pitcher Arsenal Changes for Fantasy Baseball: Pitch Mix, Movement, and Velocity

Corbin examines four fantasy baseball pitcher risers and sleepers displaying changes in their pitch mix, movement, and velocity heading into Week 3 (2024).

We've had 16 pitchers in the top-200 picks of NFBC ADP injured in the first week or so, with Sonny Gray as the only pitcher returning from an injury. Meanwhile, seven hitters inside the top 200 in ADP have been injured to begin the season. It's been brutal and we seem to have pitchers unexpectedly hitting the injured list like Nick Pivetta most recently after starting the season well.

Pitchers may be turning into the running backs of fantasy football, where some will use the zero running back or zero starting pitcher approach given the injury landscape early in 2024. That might be an interesting experiment next offseason.

Like last week's column, we'll examine the starting pitcher arsenal changes. The early data points to monitor include pitch mix changes, movement profiles, and velocity. Most of those play a role in a pitcher's stuff and skills. Thankfully, Baseball Savant provides us with easily attainable data to see it live. The process for this column will involve scouring the Baseball Savant game feeds, player breakdowns, and video to see if we notice any actionable changes that carried over from spring training or notably shifted from past seasons.

After examining the changes for these starting pitchers in the early parts of the 2024 season, we'll summarize whether we should act or be patient with the data. Again, we have a small sample of 1-2 starts in 2024, so it could be legitimate or noisy by the end of the month. Reach out on X if you have a pitcher you have questions about that may be included in a future article.

Nathan Eovaldi Threw More Splitters

In Eovaldi's start against the Rays last week, the splitters dominated the arsenal as he threw it 43 percent of the time. It's notable because Eovaldi threw the splitter at a career-high rate in 2023 (27.6 percent of the time). It could have been part of the game plan, but it's something to monitor in future outings. The visual below shows Eovaldi's pitch mix and whiff results against the Rays on April 3.

Eovaldi's splitters generated a 29.5 percent swinging strike rate on April 3 against the Rays. That's over 13 percentage points higher than his career average of 16.7 percent. Though it shows higher velocity on most pitches (about 1 mph), Baseball Savant seems to be showing the 2023 numbers and not the 2024 comparison yet. 

Though he didn't use the splitter as often on April 9 against the Athletics, it still elicited a 28.6 percent swinging strike rate to rival the four-seamer (21.9 percent) and curveball (25 percent) generating swings and misses at a high rate, as seen below.

Eovaldi often tweaked his pitch mix to involve the four-seamer, splitter, cutter, and curve making up most of his arsenal. However, the early movement profile changes horizontally might be the most notable on the four-seamer and splitter. Eovaldi's four-seamer and splitter added about two inches of arm side fade, seen below. If we think of zero as the body's midline, the negative numbers mean movement toward right-handed hitters.

Having the four-seamer and splitter move more laterally should result in weaker contact, especially against left-handed hitters. It's happening in 2024, with the bonus of whiffs on the four-seamer and splitter.

Summary

The age-old saying of process over results comes into play for Eovaldi because the process aligns with the results. Sometimes, pitchers succeed or struggle with a mixed bag of underlying metrics and pitch arsenal changes. Eovaldi fits the mold of a starting pitcher with the skills and process leading to positive results. As a middle-round pitcher going around pick 200, Eovaldi looks like an early player providing value. When healthy, Eovaldi is a solid option, and we'll continue monitoring the pitch mix and added horizontal movement on the four-seamer and splitter.

Matt Manning's Harder Slider and Sweeper

The Tigers called up Matt Manning for a doubleheader on April 4, and he threw 5.2 hitless and scoreless innings with four walks and three strikeouts against the Mets. Unfortunately, the Tigers sent him to Triple-A afterward, but he threw a harder slider and sweeper.

Manning's sweeper came in over 1 mph faster than in 2023 and a slider more than 3 mph than in 2022. Interestingly, Manning had a harder slider thrown at 85.4 mph in 2021. Regardless, Manning used the sweeping slider more often, as his second-most used offering. The sweeper has been most effective against right-handed hitters with a .266 wOBA and .315 xwOBA in 2023. 

Understandably, the sweeper doesn't fare well against lefties, evidenced by a .386 wOBA in 2023, though it came with a much better xwOBA of .206. That indicates Manning's sweeper tends to generate weaker contact against lefties, so the results should regress slightly. Even if the sweeper's performance against lefties regresses, he still may need a consistent offering via the four-seamer, curve, or splitter. 

Summary

Manning deserves a chance to be in the Tigers rotation, but he sits as their SP6. In Yahoo leagues, hold Manning in an NA spot. However, maybe he should take up a bench spot in 12- or 15-team leagues without an NA spot, given his potential and the pitcher injuries. Having two types of sliders for Manning in the sweeper and harder slider makes him an interesting option as a streamer with strikeout upside. Try to hold and be patient because of Manning's actionable changes during the offseason and in his first start of 2024.

Bryce Miller is Throwing More Splitters

Bryce Miller posted ugly results in his first start against the Red Sox. However, Miller turned it around in his second start versus the Brewers, relying on the four-seamer (35 percent), splitter (26 percent), and sinker (26 percent) that accounts for 87 percent of the arsenal. It's only two starts, but Miller bumped up his splitter usage by four percentage points on April 6.

Miller ditched the slider usage in favor of the splitter and sinker against the Brewers, and it may have been a part of the game plan. We heard about Miller working on a splitter during the offseason, so it's positive to see it translate to whiffs, evidenced by the 30 percent swinging strike rate against the Brewers. 

It's interesting to see a high zone rate on the splitter because splitters usually end up outside the strike zone. The league average for splitters in the zone in 2023 sat at 36.5 percent. Miller threw his splitter in the zone 65 percent of the time against the Brewers, but that might be an outlier outing. Regardless, Miller's splitter elicits a nasty 30 percent swinging strike rate through two starts. 

It plays well off his four-seamer and slider since the splitter sits in different zone areas to keep hitters off balance. In 2023, Miller lacked a consistent offering to attack left-handed hitters. His four-seamer allowed a .418 wOBA with the slider at .348 against lefties. He threw a changeup 10.8 percent of the time to left-handed hitters last year, and it fared decently with a .254 wOBA. However, it didn't elicit the swings and misses one would hope from the off-speed pitch to opposite-handed hitters. Miller's new splitter generates whiffs and weak contact with lefties in 2024. 

Summary

The talk about pitchers adding new pitches sometimes does or doesn't come to fruition. It's early, but we've seen these changes occur for Miller and his splitter. If there's an organization to trust for further development on Miller's pitches, it's the Mariners. Miller entered the season as a priority draft target. We love seeing the splitter usage aligning with its purpose to attack lefties for weak contact and whiffs, so hopefully, it becomes a consistent part of his arsenal with the four-seamer and slider. 

Is Ryan Pepiot's Four-Seamer Good?

Pepiot reached a career high in strikeouts (11) and whiffs (21) on Sunday at the Rockies. His four-seamer led the arsenal with a 26.5 percent swinging strike rate and the changeup finished in second at 23.8 percent. The changeup isn't surprising since it elicited an 18.9 percent swinging strike rate last season. However, Pepiot's four-seamer raises the interest level if he can establish the fastball. 

Pepiot kept the four-seamer up in the zone, pairing well with the changeup low in the strike zone. It's early, but Pepiot's four-seamer VAA went from 4.7 degrees (2023) to 4.1 (2024), moving into the average to above-average range for a fastball higher in the zone. That slight adjustment makes it more challenging for hitters to barrel up, meaning more weak contact and whiffs like we saw against the Rockies. 

Pepiot's four-seamer added about an inch of "ride," which appears to make sense with the slight changes in VAA. Whether we're looking at the vertical movement with gravity or vertical break versus the average on Baseball Savant, he made a notable four-seamer adjustment with the Rays.

Meanwhile, Pepiot's changeup isn't dropping as much, about one inch fewer than in 2023. Based on where he locates and commands the changeup, it doesn't seem to be an issue so far, given the swings and misses. We know the changeup is deadly, so it adds confidence if Pepiot improves the location and attack angle of the four-seamer. 

Summary

Pepiot entered the season as a sleeper based on joining the Rays and having a solidified role in the rotation. We've seen Drew Rasmussen, Jeffrey Springs, and other Rays pitchers have success based on tweaks made to the arsenal via movement, attack angles, and more. It might be confirmation bias in liking Pepiot before the season and seeing success in his second outing. 

However, we'll want to stay level-headed because it may come with bumps until we see more data on Pepiot's four-seamer being an established weapon to pair with the changeup. Keep tabs on Pepiot's four-seamer VAA and location because that will be the key to unlocking him from a sleeper to a breakout pitcher in 2024. 

The Graham Ashcraft Conundrum

Oh my, Graham Ashcraft had his slider generating a 20 percent swinging strike rate with the cutter at 18.9 percent against the Brewers on April 8. Unfortunately, the results looked awful with nine hits, five earned runs, one walk, and six strikeouts in 5.2 innings against the Brewers. However, it's positive to see the whiffs under the hood.

Seven of the eight whiffs on Ashcraft's slider came down and inside to left-handed hitters. That's where we want him to locate the breaking pitch to elicit swings and misses. Meanwhile, five of his seven cutter whiffs acted like a fastball, generating whiffs in the upper third of the zone. Theoretically, Ashcraft's pitch mix should perform better against righties, but he seems to attack lefties better with the slider and cutter. 

The challenge Ashcraft faced in the past involved handling right-handed hitters because the cutter and slider typically perform better against opposite-handed hitters. In Ashcraft's start against the Brewers, he often used the cutter against left-handed hitters with five of his cutter whiffs coming against lefties. Let's see if he continues locating the cutter up in the zone.

Ashcraft threw the sinker more often against right-handed hitters, attempting to jam them inside and induce weaker contact. It's (somewhat) working through two starts with .301 wOBA and .262 xwOBA allowed on the sinker against right-handed hitters.

It's also positive to see Ashcraft's slider performing well against same-handed hitters through two starts as he locates it down and away from them. That's evident by the slider allowing zero hits with a .089 xwOBA and a 21.4 percent swinging strike rate against right-handed hitters in 2024. 

Summary

Ashcraft teases us sometimes because of his stuff and nasty movement profiles. He could unlock another level if he can find a sinker or another pitch to pair well against right-handed hitters. Ashcraft remains one example of a pitcher where we look beyond the box score, assess the arsenal, evaluate the locations, and examine the skills. Don't lose hope on Ashcraft. However, it's better to bench and hold in most formats.

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