Fantasy Baseball Starting Pitcher Arsenal Changes: Pitch Mix, Velocity, and Movement (Week 7)

Corbin examines three fantasy baseball pitcher risers and sleepers displaying changes in their pitch mix, movement, and velocity heading into Week 7 (2024).

Welcome back to the weekly column, where 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 a handful of 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.

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 five starts or so in 2024, so it could be legitimate or noisy by the end of the month.

Reach out to me on X if you have a pitcher you have questions about that may be included in a future article.

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Mitch Keller Hasn't Provided the Whiffs

As a longtime lover of Mitch Keller, he hasn't taken a step forward as I hoped. He threw a complete game against the Angels, with five hits, one earned run, one walk, and five strikeouts on May 6. Keller pitched to contact in his complete game, and that's a logical approach to be efficient instead of going from strikeouts. His sinker allowed 83 percent zone contact, the four-seamer gave up 92 percent zone contact, and the cutter had 100 percent zone contact against the Angels, as seen below.

That aligns with the fewer whiffs and the lower called strikes plus whiff rate (CSW%) because an out via a ball in play is more efficient than attempting a strikeout. Keller keeps tweaking the pitch mix from start to start, with the four-seam (32.3 percent), sinker (23.3 percent), cutter (22.1 percent), and sweeper (14.6 percent). 

Last season, Keller had three pitches with a swinging strike rate above 10 percent, including the four-seamer (13.1 percent), cutter (10.7 percent), and sweeper (12.4 percent). Unfortunately, the whiffs declined in 2024, with the sweeping slider eliciting a 10.9 percent swinging strike rate and the four-seamer just under 10 percent (9.9). 

Keller's sinker and cutter allowed more contact of about 3-4 percentage points, with the four-seamer contact rate jumping nearly six points in 2024. The only pitcher allowing less contact involves the sinker, dropping three points in 2024 compared to 2023. Keller's pitch-level metrics align with the theory of his attempt to pitch more to contact in 2024. 

Keller's Four-Seam and Sweeper

Keller's pitch movement profiles theoretically suggest more whiffs and weak contact. His four-seamer has an average IVB of 15.3 inches, with an above-average amount of arm-side run at 9.5 inches. Keller's four-seamer runs into the inside of the plate for right-handed hitters, translating into weaker contact, evidenced by a .283 wOBA. 

Keller's four-seamer is slightly flatter than the average pitch, with a -4.6 degrees VAA, and located higher in the zone. In 2023, Keller threw the four-seamer in the upper third of the zone 8.3 percent of the time, which jumped to 12.6 percent in 2024. Though it's not a dominant pitch, the four-seamer looks like an offering to rely on more for weak contact. 

Interestingly, Keller's sweeper isn't sweeping as much, with three inches fewer of glove-side movement. We've noticed the swinging strike rate on the sweeper dip about 1-2 percentage points while still being an effective pitch against right-handed hitters (.233), similar to 2023 (.245). Keller locates the sweeper down and away from right-handed hitters as somewhat of a slower cutter that same-handed batters struggle to square up.

Summary

Keller's xERA of 3.89 hints at better results compared to his actual ERA of 4.41. That's similar to last season, with an ERA of 4.21 and xERA of 3.77. Though some might scoff at ERA estimators, xERA accounts for the pitcher's skills and allows us to dive deeper into the arsenal, movement profiles, and more. There's value in eating decent innings, but we would have more confidence in Keller if the strikeout skills took a step forward. Keller's four-seam and sweeper give him a foundation to build upon and keep tabs on the curveball, which generates weak contact and potentially more whiffs if he bumps up the usage. 

Edward Cabrera Continues to Lean on the Changeup

It's rare to have a starting pitcher rely heavily on the changeup like Edward Cabrera. Though Cabrera's ERA looks awful, his expected ERA indicates better ratios due to the luck factors against his favor. While we appreciate the strikeout skills, with a 12.6 percent swinging strike rate, Cabrera's early ball rate of 35.4 percent may be fluky compared to a career rate of 39.5 percent.

Cabrera has thrown the changeup at the highest rate of his career, but the results look shaky. His changeup took a 4-5 percentage point dip in swinging strike rate to 13.4 percent in 2024, which concerns us. One reason to explain the lower whiffs involves a higher zone rate of 44.8 percent, translating to more contact by opposing hitters. 

Cabrera throwing his changeup more in the zone could be an attempt to improve his control. However, Cabrera hasn't increased the zone rate on his other primary pitches in the four-seam, curveball, and slider. The changeup's movement profile hasn't changed, so it seems like a concerted effort to locate his best pitch. 

Besides the dip in swinging strike rate, Cabrera's results on the changeup against right-handed hitters ballooned to a .420 wOBA compared to .392 (2023) and .284 (2022). However, Cabrera's slider is eye-popping, with a career-high swinging strike rate of 21.6 percent. His slider performed well in the past but lacked this level of whiffs.

The same trend occurred against lefties for the changeup where he throws it 49.1 percent of the time, allowing a .272 wOBA with a worse xwOBA of .378. When a pitcher uses a pitch at a high rate against both sides of the plate with poor results, it makes us wonder if they should ditch or revamp it. Historically, Marlins starting pitchers leaned into their changeups as a new or improved pitch. Cabrera may throw the changeup less often in the zone to induce hitters to chase. 

Slider Location

Since Cabrera's slider movement profile hasn't changed, the success comes from locating it better. In 2023, Cabrera threw the slider more in the middle of the zone, and hitters feasted on it. The visual below shows Cabrera's slider zone profile with the results in 2023.

Meanwhile, Cabrera has been locating the slider down and away to right-handed hitters most of the time. That led to much better results against righties with a .149 wOBA (2024), down from 2023 (.224 wOBA). It could be fluky, but the slider performed better in 2024, as he threw it nearly five percentage points more than in 2023.

That aligns with more slider whiffs, as mentioned earlier, which somewhat makes up for the changeup struggles. If Cabrera has a consistent changeup and slider, we might have something special here.

Summary

Besides the changeup usage and zone rates, the rest of Cabrera's arsenal hasn't shifted from a movement profile standpoint. It's early with small samples in 2024, so the ball rate improvements might be a moot point here. Cabrera is locating the slider better, leading to better results against right-handed hitters, which he primarily throws against same-handed batters. Some potential changes seem fixable for Cabrera, so keep tabs on it.

Though fantasy managers weren't starting Cabrera against the Dodgers, he left early due to biceps discomfort in his throwing arm. Injuries have been an issue for Cabrera, so this concerns us. The Marlins have a few starting pitchers recovering from injuries or in Triple-A to take Cabrera's spot. Cabrera's injury concerns align with the roller coaster of having him on our fantasy squads.

Cole Irvin is Succeeding, But How?

Cole Irvin has three consecutive scoreless outings against the Reds, Athletics, and Royals. Irvin has solid control, evidenced by his 32.9 percent ball rate. However, Irvin elicits a career-low swinging strike rate of 6.1 percent, three percentage points below his career norm. 

With Irvin struggling to generate whiffs, we find only two pitches with a swinging strike rate above 7 percent. The changeup highlights the arsenal with a 14.8 percent swinging strike rate, yet it's one of his least-used offerings at 11.3 percent, mainly via right-handed hitters. Irvin's four-seamer broke the 7 percent threshold in swinging strike rate at 7.8 percent. A control and command pitcher like Irvin can make it work, but we wish for slightly more whiffs to have more confidence.  

Irvin's curveball nearly doubled in usage in 2024 as his most used offering. The results against the curveball have been mixed, with a .258 wOBA against right-handed hitters and .336 wOBA versus lefties. His curveball boasts above-average glove-side sweep to generate weak contact, which hasn't occurred. 

Though we're in the era of sliders, sweepers, splitters, and induced vertical break (IVB) on four-seamers, Irvin bucks the trend with his curveball usage. He uses his curveball for called strikes, with a 22.5 percent called strike rate and a 30 percent called strike plus whiff rate. 

That's important to understand how Irvin uses the curveball because he throws in the middle of the plate 11.1 percent of the time, with most going inside to lefties at 25.9 percent. That's slightly better than 2023, when he threw it in the middle of the plate 19.8 percent of the time. The curveball had more called strikes (25.4 percent) in 2023, and it unsurprisingly hasn't been a priority for whiffs in Irvin's arsenal.

Summary

We've witnessed control and command-focused pitchers like Irvin, Kyle Hendricks, and others outperforming their expected metrics. Like Spencer Turnbull in last week's column, Irvin is making it a tough decision on whether he stays in the starting rotation with Kyle Bradish and John Means returning from their injuries. Maybe it's a bias, but trusting a pitcher like Irvin falls into the results-over-process bucket, so be careful.

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