Starting Pitcher SwStk% Gainers — Through May 21, 2023

When I’m reviewing a breakout starting pitcher, especially one who has raised his strikeout rate, I want to see a SwStk% surge. I get skeptical of pitchers who increase their strikeout rate without a corresponding increase in SwStk%. The higher strikeout rate is therefore usually due to some combination of an increased called strike and/or foul strike rate, both of which aren’t as skills-driven as SwStk% is. So let’s review the pitchers who have increased their SwStk% the most compared to 2022. Have they also enjoyed an increased strikeout rate?

SwStk% Gainers
Name 2022 K% 2023 K% 2022 SwStr% 2023 SwStr% SwStk% Diff
Spencer Strider 38.1% 41.5% 15.2% 20.4% 5.2%
Louie Varland 19.8% 26.3% 8.5% 13.4% 4.9%
JP Sears 16.0% 25.1% 8.5% 12.3% 3.8%
Domingo Germán 19.2% 26.1% 11.4% 15.2% 3.8%
Joe Ryan 25.0% 30.4% 11.4% 14.7% 3.3%
Reid Detmers 22.6% 29.8% 11.1% 14.4% 3.3%
Sonny Gray 24.0% 29.6% 9.2% 12.3% 3.1%

Was Spencer Strider supposed to be this good?! It’s not normal for a starting pitcher to post a SwStk% over 20% and strikeout rate over 40%. His pitch mix is similar to last year, with a couple of more sliders at the expense of his fourseam fastball. It’s pretty incredible that he’s been essentially a two-pitch guy and has been this dominant. Both his fourseamer and slider have posted higher SwStk% marks compared to last year, pushing each to absolutely elite territory. I guess you don’t need a third pitch when your two pitches are that good! Although I joke about him only having two pitches, he has thrown a changeup infrequently, and that pitch itself has recorded a SwStk% over 20%! I guess batters are so set on his fastball, they have no chance to slow down their swing when the changeup surprisingly comes.

I hope you listened to me when I told you to “pick him [Louie Varland] up if he’s still available, especially if you can confirm his fourseam velocity remains 95+”, which I demanded in my article a couple of weeks ago! His fastball did average more than 95 MPH in his first two starts after I penned the article, but declined to 94.5 MPH in his last start. That said, he has posted a 3.12 ERA since with 17 strikeouts. The increased velocity is most certainly playing a role here, as his fourseamer’s SwStk% has risen into double digits, after finishing at just 6.6% during his cup of coffee last year. It’s apparently also improved his slider and changeup’s whiffiness, as both pitches are now well into double digits, after finishing in the high single digits last year. I remain bullish for as long as he can hold the velocity gain.

JP Sears’ velocity has remained stable, at least on his fourseam fastball, though his changeup and slider have both gained a bit of speed. The big difference is he has swapped out some changeup usage for even more slider usage. That’s odd though because his changeup has actually generated a higher SwStk% than his slider this year, and also sitting at a much higher mark than last season. What’s really driving his SwStk% is a near doubling of his fourseam SwStk%, which now sits in double digits. Given his crazy high FB%, it stands to reason he’s throwing his fastballs higher in the zone, though he doesn’t exactly have the velocity to be doing that. I would rather see higher SwStk% marks from his secondary pitches, so I’m skeptical he’ll maintain this strikeout rate level.

After posting his lowest mark, excluding his small sample 2017 debut, last year, Domingo Germán’s SwStk% has rebounded and sitting at a career high. Interestingly, it has come despite a career worst fourseam velocity. In fact, all his velocities are down, except his curveball, which is actually up at a career high, and is also his most thrown pitch. I can’t recall seeing a pitcher whose pitch velocities were all down, except for one pitch that was up, and it just so happens to be their most thrown pitch. Perhaps this is an intentional change to throw a harder curveball. The pitch’s SwStk% is sitting at its second highest mark of his career, though it’s not significantly higher than his career average. It’s really been his changeup and sinker, both of which are sitting 2.4% higher than his career averages. It’s a good sign coming off a down 2022, but I foresee some regression over the rest of the year to more in line with his history.

For the second straight season, Joe Ryan has gained velocity, which is a big deal considering he’s been below average in that department. He has also thrown a new slider and stopped throwing his changeup, so it’s been quite a different look from him this year. The increased velocity has been amazing for his fourseam, which sports an elite 16.2% SwStk%. The pitch is still below average in velocity, and yet has been able to generate an elite SwStk% anyway. While his slider’s SwStk% has dipped, his new splitter has been strong and significantly better than his changeup at generating swings and misses. That seems to have been a good trade.

I was all over Reid Detmers when I learned his velocity was up during spring training. While it hasn’t yet led to a breakout ERA, the skills have improved dramatically. He has also thrown both his fastball and curveball less often, in favor of his slider, which has been incredible, recording a 24.1% SwStk%. Surprisingly, the increased velocity hasn’t resulted in a higher whiff rate for his fastball, which sits at just a 7.4% SwStk%, versus a 9.4% mark last year. His curveball still stinks too, which is weird considering that was the pitch he was known for as a prospect. That .366 BABIP should improve, while the 61.4% LOB% rises, making him an excellent trade target, while his ERA stands significantly above both his SIERA and xERA.

At age 33, Sonny Gray has posted the highest SwStk% of his career, which has led to the second highest strikeout rate of his career. His fourseam velocity has rebounded, and is at its highest since 2020. He has also switched up his pitch mix, throwing his cutter into double digits for the first time, and increasing the usage of his changeup and slider, at the expense of his fourseamer and sinker. That sounds like a good change for SwStk%. His changeup remains weak at generating whiffs, while his slider’s SwStk% has rebounded off last year’s low, but is still below his career mark. His cutter has been decent, certainly better than the pitches he reduced his usage of. Overall, the pitch mix change has clearly led to more swings and misses, but his individual pitches aren’t really any better than they have been in the past.

Mike Podhorzer is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year. He produces player projections using his own forecasting system and is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. Follow Mike on Twitter @MikePodhorzer and contact him via email.

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8 days ago

Really not gonna mention the sticky subject in German’s blurb?

8 days ago
Reply to  O'Kieboomer

Seems germane to German’s K rate.

If the velocity isn’t up, and it’s a crazy curveball behind the K spike, maybe what’s helping him spike that curve is not exactly legal?