Fantasy Baseball Starting Pitcher Arsenal Changes (Week 19): Pitch Mix, Velocity, and Movement

Corbin examines two fantasy baseball pitcher risers and sleepers displaying changes in their pitch mix, movement, and velocity heading into Week 19 (2024).

Welcome back, RotoBallers, to my weekly "Starting Pitcher Arsenal Changes" article series for Week 19 of the 2024 fantasy baseball season. Today's article will discuss Grayson Rodriguez and Luis L. Ortiz. 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're over halfway through the fantasy baseball season, causing fantasy managers to make crucial decisions for the second half of the season. 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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Grayson Rodriguez's Revamped Slider

In 2023, Rodriguez threw a sweeper 24.7 percent of the time against right-handed hitters, translating to a .165 wOBA. His sweeper came in averaging 82.3 mph with 36.7 inches of horizontal movement and 11.3 inches of downward movement. Rodriguez ditched the sweeper in 2024 and used a revamped slider (86.7 mph) with 34.5 inches of glove-side movement and hardly any drop.

Unfortunately, the results have been poor versus the slider against right-handed hitters. That's evident in Rodriguez's slider, which allows a brutal .383 wOBA (.371 xwOBA) versus righties as his second-most-thrown pitch at 28.8 percent. Interestingly, Rodriguez's slider elicits a decent 17.2 percent swinging strike rate in 2024, similar to the sweeper in 2023 (15.1 percent).

Since the whiffs stuck around with the revamped slider, it's possibly fluky with poorer results in 2024. Though there's a movement profile change with the breaking ball, hitters have been crushing the slider. That's evident in the 91 mph average exit velocity against the slider for right-handed hitters, up from 83.7 mph in 2023. There's some misfortune for Rodriguez's slider since it allowed zero home runs in 2023, ballooning to a 26.3 percent HR/F in 2024.

The guess regarding the massive decline in results would be related to the pitch location for the sweeper compared to the slider. In 2023, Rodriguez peppered the sweeper down and away from right-handed hitters outside the zone 46.5 percent of the time, translating into a .037 wOBA. While Rodriguez locates the slider 43.6 percent of the time in the same area and allows a .261 wOBA, hitters have been destroying the breaking ball when in the zone.

Rodriguez's sweeper allowed a .201 wOBA in the zone in 2023 compared to the slider, resulting in a .458 wOBA (.459 xwOBA) in 2024. He increased the zone rate by 10 percentage points in 2024, and hitters made 12 points more zone contact (89.2 percent). It may benefit Rodriguez to throw the slider less often in the zone as the season progresses to see if the results follow while maintaining or increasing his swinging strike rate.

Rodriguez's Slight Release Point Change

With most of Rodriguez's pitches, we've seen a slight release point change, with the vertical release point on the four-seam dropping by over two inches and the slider vertical release shifting by over two inches. That led to an inch more extension on each pitch, which might be fluky or cause the movement profile to move slightly.

With the slider's vertical release point dropping by two inches, it makes sense to see the movement profile change from the sweeper to the slider. That led to fewer inches of sweeping movement on the revamped slider, with less downward movement by nearly five inches, mostly due to the added velocity.

We've seen Rodriguez shift his four-seamer release points by about one inch from 2023, leading to over an inch more arm-side run on the heater. It's a minimal change, but Rodriguez's four-seamer has resulted in better outcomes with a .339 wOBA (2024) compared to a .405 wOBA (2023).

Summary

Rodriguez's 2024 ERA (3.8w) is similar to his 2023 xERA of 3.89. His xERA (3.69) is slightly better than his actual, with mostly gains via the strikeout skills. Rodriguez added 1.5 percentage points in the swinging strike rate (14.1 percent), indicating high-end skills. If Rodriguez adjusts the slider zone rate and location, which is easier said than done, it could unlock another level of upside. The top prospect has been living up to his potential. It's positive to see him improve from his rookie year, so we should be buying into the arsenal changes in 2024.

Luis L. Ortiz Throws a New Cutter

Before 2024, Ortiz threw a cutter only four times in 2023. However, he evenly distributes the cutter usage against right-handed hitters (17.6 percent) and lefties (23.1 percent). Ortiz's cutter doesn't have an above-average movement profile. However, we've seen it become one of Ortiz's best pitches.

Against right-handed hitters, Ortiz's cutter allowed a .234 wOBA compared to a .256 wOBA versus lefties. It's been his best pitch results-wise against righties and his second-best versus lefties. Ortiz's sinker has better results (.211 wOBA, .322 xwOBA) than the cutter against left-handed hitters among pitches he throws at a double-digit rate. Though Ortiz's cutter doesn't elicit a high rate of whiffs (7 percent swinging strike rate), it helps to limit hard contact.

Ortiz's Pitch Movement Changes Due to Shifts in Release

Ortiz's slider lost over two inches of downward movement while adding an inch of glove-side cut compared to 2023. It's not a massive movement profile change, but there appears to be a shift in release points. Ortiz lowered his vertical release by nearly three inches (2.76) while having his horizontal release point move over three inches farther away from the midline of his body.

He is using a more three-quarters release point, aligning with the movement profile change on the slider. If we visualize Ortiz's release moving away from the middle of his body, he likely can't get over the top of the ball to add downward movement to the slider.

We've seen similar release point changes across all pitches, not isolated to one offering. With the release changes, Ortiz's four-seamer lost nearly two inches of induced vertical break (11.4 inches), though it already had poor IVB. His four-seam tends to generate more arm-side movement than the average four-seamers by nearly four inches, with the league average around 7.7 inches.

Ortiz's four-seamer possessing tons of horizontal arm-side movement should lead to weaker contact. The four-seamer allows a .289 wOBA (.244 xwOBA) against right-handed hitters and throws it 17.2 percent of the time. Meanwhile, Ortiz tosses his four-seamer most often against lefties (35.9 percent), with decent results (.290 wOBA, .337 xwOBA). His four-seam almost acts like a sinker with the amount of arm-side run on the fastball. It could be noisy, but Ortiz's four-seamer HR/F fell to 6.7 percent (2024) from 21.9 percent (2023), given the movement shift and release point changes.

Summary

The stuff for Ortiz doesn't overwhelm us, though we found interesting arsenal nuggets. Ortiz has been fortunate with a 2.57 actual ERA compared to his 4.18 xERA. That's due to the luck factors in his favor (H%, S%) combined with mediocre skills. Ortiz's cutter is a positive addition against both sides of the plate. It's an intentional move adding the cutter since it works well with his three-quarters arm slot and release point changes. Ortiz's starting pitcher arsenal suggests he's more of a deep-league streaming pitcher with little strikeout upside.

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