Strikeout Rate Surges to Believe In

There is more to pitching in fantasy than just strikeouts but ratios and wins can be fickle little elves from season to season, mischievously relying on more things beyond a pitcher’s control. The whiffs, however, tend to be more predictable year-to-year. Or, at least, it’s easier to make more direct connections between changing results and changing stuff.

Strikeout rates also start to stabilize quickly, at around 60 batters faced. Note that they only start to stabilize at that point, so while the sample may start being meaningful, it becomes much more so with more batters faced. But the comparatively lower threshold for strikeouts makes it more possible to compare them with 2020’s mini-season.

Here are the starting pitchers in 2021 (min 75 IP) that saw at least a two-point increase in their strikeout rate compared to 2020.

Starting Pitchers 2020-2021


Logan Webb, SF, 57 ADP

2020: 18.7% K%, 2021: 26.5% K%

I like to imagine a 2021 season in which Webb has a lower ADP because he didn’t dominate over two starts in the playoffs, posting a 0.61 ERA and 32.1% K% over 14.2 IP. Because recency bias is a thing and it seemed that Webb struggled towards the end of the regular season, allowing at least 4 ER in three of his final six starts. But the 4.50 ERA over that stretch was backed by a 2.14 FIP and 2.71 xFIP, while Webb’s big jump in strikeout rate never really stopped trucking.

The increase in strikeouts came with a change in pitch mix, as the four-seamer got phased out for more of the elite sinker in the second half. But it was more of his improved slider that makes me confident the new strikeout rate is here to stay.

Webb increased his slider usage from 24.3% in the first half, to 29.8% in the second half after inconsistent use in 2019-2020. But it wasn’t just more use, it was also thrown about a tick faster (as was his sinker and changeup) and at a new vertical release point, with Webb’s extension increasing from 6.0 ft to 6.7 ft.

The slider’s raw and horizontal movement decreased but when compared with pitches thrown at similar velocity and extension, it went from 1.4 inches more vertical break than average to 2.3 inches above average. Webb’s sinker also increased its extension from 6.5 ft to 6.8 ft, with the release point changing on both planes:

All of Webb’s pitches were thrown harder and with more vertical movement, being released at more similar points that are now closer to the batter. Defending against the sinker is hard enough but the synergy of his slider/changeup combo has turned the former into a wipeout pitch:

The slider had a 15.1% SwStr% in 2019 (n=159) and an 8.5% SwStr% in 2020 (n=153) but jumped to a 22.1% SwStr% in 2021 that stayed virtually identical from half to half. That was the 10th-highest among starting pitchers (min n=250) and his 46.9% Whiff% was the 4th-highest.

Given that his groundball-heavy sinker should continue getting him deep into games – Webb completed at least six innings in 16-of-26 starts – a strikeout rate in the 25% range is plenty. His playoff run might have inflated his draft price but I’m still comfortable paying it.

Dylan Cease, CHW, 85 ADP

2020: 31.9% K%, 2021: 17.3 K%

The quality of his stuff wasn’t a secret but Cease had yet to put it together until now. No qualified starter jumped his strikeout rate more than he did in 2021, increasing 14.6-points compared to 2020, with his 29.5% K% from the first half increasing to 35.5% K% in the second.

Cease got increased whiffs from across the board, with all four of his pitches setting career highs in SwStr% and Whiff%, while his whiffs on balls in the zone also increased significantly:


2019-2021 In-Zone Rates

2019 zSwst% 2020 zSwst% 2021 zSwst% 2019 zWhf% 2020 zWhf% 2021 zWhf%
4-Seam 12.9 12.9 16.4 17.2 17.5 21.8
Slider 11.3 11.3 19.2 18.8 19.2 33.0
Curve 9.4 3.2 12.6 21.7 7.7 22.6
Changeup 21.9 16.7 27.1 29.2 30.8 43.3

Both of Cease’s breakers have had plus vertical movement prior to last year but the big change was in his four-seamer, which was down a tick in velocity from the shortened 2020 season but was still in line with his average from 2019. But the rise was significantly up in 2021, getting 18% more movement than average, compared to -2% in 2020 and -9% in 2019.

And as the movement went up, so has his confidence in attacking the zone and with better command:

The increased movement and quality of his four-seamer make his curveball and slider that much more effective, with the latter, in particular, driving Cease’s fancy new strikeout rate. The slider had a 22.4% SwStr% in 2021 that was up nearly seven points and was the 8th-highest among qualified starters.

Cease’s overall fantasy value will also depend on him continuing to limit walks (and blowups) but a 30% K% gives you a lot of wiggle room in case the ratios stay below average.

Patrick Sandoval, LAA, 224 ADP

2020: 20.8% K%, 2021: 25.9% K%

The 25-year-old left-hander has never pitched a full season, pitching more innings in 2021 (87 IP) than he had in 2019-20 combined (76 IP). But it was his most successful season, making 14 starts after moving to the rotation in May, posting a 3.39 ERA (3.63 FIP) and 1.18 WHIP while in the rotation. Unfortunately, his season was ended early by a back injury in August, so our sample is small but Sandoval did make some significant adjustments from what we’ve seen before.

At first glance, the five-point increase in Sandoval’s strikeout rate looks like a small-sample correction more than a skills jump, as he ran a 24.9% K% in 2019. But the more impressive jump was a 15.2% SwStr% that was up from 12.7% in 2020, and 13.4% in 2019. If he’d qualified, that would’ve been the sixth-highest mark among starting pitchers.

Sandoval may have had a similar strikeout rate in 2019 but he got there in a different way in 2021, over halving his four-seamer use in favor of a new sinker and consequentially adjusting his pitch mixes to both right- and left-handers:

2019-2021 Pitch Mix Splits

2019 v L 2020 v L 2021 v L 2019 v R 2020 v R 2021 v R
4-Seam 48% 39% 19% 46% 49% 26%
Sinker n/a n/a 30% n/a n/a 15%
Changeup 13% 8% 11% 37% 33% 37%
Curveball 8% 7% 7% 15% 8% 11%
Slider 31% 46% 34% 3% 11% 11%

It’s not as simple as saying that his results got better because he added a great pitch, as the sinker returned fairly mundane results. A .384 wOBA and .381 xwOBA were both in the bottom-third among starters who threw at least 200 sinkers, though it was better on contact, with a .333 wOBAcon and .363 xwOBAcon that were both in the top third.

But going back to Sandoval’s increase in SwStr%, a lot of that overall increase came from the sinker getting above-average whiffs, particularly in the zone, with a 10.1% zSwStr% that was 12th-highest and a 16.5% zWhiff% that was sixth.

Depending on whiffs from your sinker isn’t an idealized plan of attack but Sandoval was much better versus LHH in 2021 and I think his seam-shifted addition was the reason why:

Looking at the spin-based movement on the left, Sandoval’s four-seamer had an 11:15 average spin direction in 2021, which was the same as both his spin-based and observed movement in 2020. But his observed movement has shifted to 11:45 in 2021, with the +30-minute deviation implying that aerodynamic forces are coming into play.

This might be more promising when combined with the -45-minute deviation on his sinker (75-minute total deviation), as the deviations are going in opposite directions. As Barton Smith (and his muse, Jared Hughes) have discussed, pitchers can use the seams to “push” their four-seamer and sinkers in opposite directions, possibly increasing the effectiveness of both when tunneled in an ideal manner.

This is notable for Sandoval because the addition of the sinker gives him something else to push in on left-handers, where previously he only had the changeup, with the four-seamer now moving away with the slider. A once muddled movement profile now seems like a much more effective mix:

Once again, small-sample warning but Sandoval faced 107 left-handers in 2019-2020, allowing a .378 wOBA and .583 SLG, with a 6.70 FIP and 1.46 WHIP. Against 102 LHH in 2021, those numbers dropped to a .227 wOBA, .301 SLG, with a 3.89 FIP and 0.69 WHIP. And a lot of those changes were driven by much better results against his four-seamer and changeup.

Left-handers posted a .703 SLG (.783 xSLG) and .464 wOBA (.509 xwOBA) against his four-seamer from 2019-2020 but dropped to a .400 SLG (.408 xSLG) and .307 wOBA (.364 xwOBA) in 2021. The changeup didn’t allow a dramatic difference in SLG% but dropped from a .397 wOBA (.373 xwOBA) to a .278 wOBA (.319 xwOBA), with a 29.3% SwStr% that was a three-point increase.

The spin-direction deviation change in his four-seamer and addition of the sinker seems like purposeful changes to best maximize his pitch mix and better handle left-handers. And while a repeat of his strikeout rate from 2021 would be just fine, I still think there is some more ceiling in it.

Sandoval is on track to enter spring training fully healthy and given the state (and health-tendencies) of the Angels rotation, he’ll likely get every opportunity to stay there all season. With solid ratios and strikeout upside, a post-200 ADP doesn’t seem too rich.

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