Pitcher Arsenal Changes for Fantasy Baseball (Week 4): Pitch Mix, Movement, and Velocity

Injuries aside, starting pitchers have blown up the ratios. That's especially true for some higher-end starting pitchers based on ADP and expectations, including Jesus Luzardo, Luis Castillo, George Kirby, and Chris Sale. One quick way to examine whether the struggles might be luck or skill issues involves scraping the FanGraphs data over the past week or two. The data below is from starting pitchers from April 7 through April 16, sorted by the largest difference in FIP and ERA as a starting point.

There's a lot of information here, but pitchers like Garrett Crochet have dominated with quality skills and a mixed bag for the luck factors. Meanwhile, Castillo, Kirby, and Sale might be struggling due to luck factors not in their favor. It allows us to dive deeper into Castillo, Kirby, and the Mariners' starting pitcher issues. Though we won't dive into these pitchers on the list, we want to remind fantasy managers to have patience in this long game we call fantasy baseball. Don't panic with early-season struggles, especially if it's a skilled pitcher.

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

MacKenzie Gore's Improved Fastball

The former top prospect graded out as having a plus fastball in the minors, but it shifted to another level with more velocity and movement profile changes. MacKenzie Gore matched a career best in strikeouts at 11 with the second-most whiffs (20) of his career. He also tied a previous high of 12 whiffs on the four-seamer in a game during his career.

Yes, it came against the Athletics. However, it's still positive to see him dominate against weaker competition. Furthermore, nine of Gore's 12 four-seamer whiffs ended in the upper third of the zone, with some slightly above. That's an ideal location for the four-seamer for Gore to optimize the way he attacks hitters with the fastball. 

Besides Gore's four-seamer velocity jumping by 2.0 mph, it added nearly an inch of Induced Vertical Break (IVB), with slightly more armside run. His lower vertical and horizontal release points contributed to having the four-seamer improve. 

Where the four-seamer changes matter come against right-handed hitters. Gore's four-seamer allowed a .346 wOBA in 2023 against righties compared to .284 in 2024. Though Gore's fastball continues to struggle against left-handed hitters with a .536 wOBA (2024) and .465 wOBA (2023), the slider (.225 wOBA, .273 xwOBA) and curveball (.451 wOBA, .107 xwOBA) have performed well in 2024.

Since it's early, there's a chance the slider and curve results regress more toward the career averages. We say this to temper expectations with Gore, though we love the four-seamer changes via velocity, vertical approach angle, and IVB if he continues to locate it up in the zone. 

The final notable change for Gore involves the added slider velocity from 88.6 mph (2023) to 91.5 (2024). Unsurprisingly, his slider lost over four inches of drop. It's a small sample, but Gore's slider elicits a 21.4 percent swinging strike rate. That's five points above his career average for the slider. 

Part of the slider's success might be related to its location. Gore's slider plot shows that, as he peppered it down and away from left-handed hitters in 2023 and 2024. It's that classic breaking balls down in the zone with fastballs up in the zone, which typically could translate into an optimal profile. 

Summary

Gore's four-seamer changes look awesome, especially if the approach angle and IVB stick with the added velocity. Hopefully, his breaking pitches play better off of the four-seamer, though he needs some consistency against both sides of the plate. It's hard to suggest buying high on Gore since we haven't seen the near-elite level, even in small samples. However, Gore is making actionable changes worth watching, with the four-seamer likely living up to expectations in 2024. The breakout season looks like it's coming soon. 

Casey Mize Added Velocity

It's been so long since the Tigers had a trio of prospect arms headlining their farm system, including Casey Mize, Tarik Skubal, and Matt Manning. Unfortunately, injuries and struggles impacted their ascent until Skubal posted near-elite results to close out 2023. Mize's early results haven't looked great, with underwhelming skills, too. That's evident by his 7.1 percent strikeout minus walk rate and 8.2 percent swinging strike rate. 

However, the most notable aspect of Mize involves the added velocity of his four-seamer from 93.4 mph (2022) to 95.8 mph (2024). With the increased fastball velocity, Mize added nearly two inches of (IVB). It's pushing toward the above-average range of around 18 inches, with the higher spin rates to back it up. 

Mize's better fastball via velocity and IVB should lead toward whiffs and weaker contact. Though it hasn't translated to more whiffs, hitters have chased the four-seamer 29.8 percent of the time compared to a career chase rate of 20.6 percent. He has been pounding the zone with the four-seamer, given the career-high 60.2 percent zone rate. It's like about where Mize has been locating the four-seamer.

Mize's four-seamer struggled against right-handed and left-handed hitters in the past, but it improved in the small 2024 sample. That's especially true against left-handed hitters.

Mize's other weapon against lefties, the four-seamer, which pairs well with his splitter, gives us slightly more confidence. It's early, but Mize's splitter elicits whiffs at a career-best rate, with an 18.9 percent swinging strike rate. That's over six points above his career average on the splitter. 

Unfortunately, the four-seam hasn't fared well against right-handed hitters, giving him same-handed hitter split issues. Part of it may involve trouble locating the four-seamer and slider because he throws them often in the middle of the plate and hitters crush them. It seems fixable to stop throwing the four-seamer and slider often in the heart of the plate, where hitters destroy those pitches. 

Mize's slider should generate more swings and misses with the breaking ball above-average vertical movement. However, Mize's slider induced a 4.3 percent swinging strike rate in 2024 compared to a career average of 10.5 percent. His slider velocity stayed the same, but the breaker added over two inches of drop. The only aspect that changed has been the vertical release point, going from 5.4 feet (2022) to 5.54 feet (2024).

Mize's release point changes led to more than an inch of extension for all pitches. It might be an attempt for Mize to garner a more over-the-top release point, leading to more topspin on the slider seen with the added drop. 

Summary

Mize might provide more name value than fantasy value, though it's still early in 2024. It's worth holding, benching, and streaming Mize in deeper formats. However, Mize might be a pitcher to churn if we find better options. The skills of the added four-seam velocity, slider movement profile, and filthy splitter theoretically should or could come together to unlock a high-end starting pitcher in spurts. 

Palms Aren't So Sweaty for Spencer Arrighetti

After struggling in his major league debut, Arrighetti allowed two earned runs, two walks, and five strikeouts across four innings against the Braves. Though it's not the most eye-popping start, he showed some intriguing underlying metrics via the four-seamer, cutter, and curveball. Arrighetti elicited an 11.4 percent swinging strike rate in his debut outing compared to 17.2 percent against the Braves on April 15.

Evaluators graded Arrighetti's fastball and slider as his two best pitches as a prospect. Baseball Savant may be classifying the cutter as his slider. Unsurprisingly, the four-seamer (12.8 percent swinging strike rate) and cutter (33.3 percent swinging strike rate) led the arsenal, accounting for 12 out of his 15 whiffs. 

In the minors, his four-seam had a 9.2 percent swinging strike rate, with the cutter at 13.2 percent in 2023. Both pitches hovered around a 4 percent swinging strike rate in 2024 before being called up. Arrighetti reportedly used some deception with tons of extension (7.2 feet). He threw the four-seamer up in the zone, which theoretically should play well given his high-end extension. 

Arrighetti's four-seamer has below-average IVB, with the above-average range being closer to 18 inches. In 2023, Arrighetti's four-seamer had 14.7 inches of IVB, with 15.5 inches in 2024. Through his first two starts in the majors, the four-seamer IVB sits closer to the brief minor league sample in 2024.

Some right-handed pitchers with similar four-seamers in 2023 and 2024, including IVB and armside run, would be Emmet Sheehan (15.6 IVB, 11.1 ARM), Keaton Winn (15.7 IVB, 10.9 ARM), and Max Scherzer (15.8 IVB, 10.8 ARM). It gives us context on how effective Arrighetti's four-seamer could be if it continues to elicit whiffs while locating the fastball in the upper third of the zone. 

Summary

Most fantasy managers likely dropped or refused to acquire Arrighetti after the brutal first outing, and they might feel the same after the second. However, when we examine Arrighetti's arsenal at a deeper level, he warrants a bit more intrigue. The wild card for Arrighetti is the curveball, using it for called strikes and mixing up the velocity bands, with a 46 percent called strike plus whiff rate (CSW%). In his first start, the sweeper seemed interesting, too, with a 19 percent swinging strike rate. Again, we're dealing with small samples, so this could be meaningless in a week or two, especially when Justin Verlander and Framber Valdez return to the rotation. 

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