Starting Pitcher SwStr% Gainers & Decliners — April 28, 2026

If I could choose just one underlying skill-based metric to evaluate a starting pitcher on, it might very well be SwStr%, especially for fantasy purposes, assuming your league uses strikeouts in some shape or form. Obviously, there’s more to effective pitching than just generating whiffs. However, with a -0.42 correlation with ERA and 0.85 correlation with strikeout rate among qualified pitchers from 2021 to 2025, it tells you a whole lot all by itself. So with that in mind, let’s peruse the starting pitchers that have experienced the greatest gains and declines in SwStr%.

Injury delayed Matthew Boyd’s start to the season, but in three starts so far, his SwStr% and strikeout rate have skyrocketed. Surprisingly, he’s throwing his four-seamer significantly more at the expense of his slider and curveball, which you would think would have a negative effect on those rates. His Stuff+ is also just below his mark last year and essentially a match for his career. The only real difference is an elite Location+, so perhaps he’s simply locating so extraordinarily well that even without improved stuff, it’s leading to more whiffs and strikeouts. I wouldn’t bet on that to continue and would actually prefer to see fewer fastballs.

Randy Vásquez has appeared on a number of these leaderboards as his increased velocity has stuck so far. It’s still weird to me that his Stuff+ is only up marginally and remains below league average. So I still have a hard time believing he could maintain such a strong SwStr% and strikeout rate, especially considering his Location+ is barely above average. With a 1.88 ERA due for major regression even if he maintained his underlying skills, I would be nervous starting him outside of NL-Only leagues.

How on Earth has Brayan Bello posted a higher SwStr% than strikeout rate?! I’m not sure I’ve ever seen that before. And that SwStr% is at a career high, yet the strikeout rate has collapsed to a career low, while his ERA stands at 9.00! If Payton Tolle continues to pitch well as the team awaits for Sonny Gray’s return, Sox fans are going to bring out the pitchforks if it’s Bello that keeps his rotation spot.

Speaking of Payton Tolle! The sample sizes are tiny here — last year was only 16.1 innings and this year has been one six inning start. I’m not sure you could get a better start than a 19.4% SwStr%, 39.8% CSW% and 50% strikeout rate, with just a 4.5% walk rate. Tolle’s velocity was up marginally from last year and he relied heavily on his fastball and sinker. I don’t know if that’s a good thing or not — on the one hand, he dominated without throwing his secondaries very often, which is impressive, but on the other, that’s likely not sustainable, so he’s going to need to throw those secondaries more to maintain anything close to that level of success. With a 115 Stuff+, I would be buying everywhere.

A lot of us wondered how Jack Leiter, blessed with high 90s velocity and clearly strong stuff (above average Stuff+ too), managed just league average SwStr% and strikeout rates last year. No Longer! His pitch mix has changed a bit, but his Stuff+ is about the same, while his Location+ has improved slightly. All in all, not much has truly changed, but perhaps he has learned how to use his repertoire better to earn swings and misses. This is much closer to what we all expected.

Wow, Jacob Misiorowski leads qualified pitchers in SwStr% and his strikeout rate is all the way up to 37.2%. Oh, and he has his walk rate in single digits…for the first time in his professional career. He’s throwing his four-seamer a bit more at the expense of his changeup, but that’s really the only change. His Stuff+ remains absolutely elite. It’s hard to believe anyone could sustain a strikeout rate this high, though it’s been done before. If anyone could, he certainly has the stuff to add his name to that list.

Was Cam Schlittler supposed to be this good?! Weirdly, he’s generated a very low CStr%, so his CSW% is actually averageish and makes me wonder how sustainable a 30%+ strikeout rate is. His velocity is down slightly from last year’s MLB debut, but that itself was up from where he had been at Triple-A, and his velocity is still higher than where it was then as well. He has changed his pitch mix, throwing his four-seamer and curveball less, and upping his cutter and sinker usage. From a Stuff+ perspective, that change shouldn’t matter much. But man, all his pitches have a Stuff+ of at least 103, while his Location+ has also surged to match his Stuff+ at 113. Given his historically higher walk rates, and 10.2% mark last year, it’s shocking to see a tiny 3% walk rate right now. I’m eager to see how the rest of his season unfolds.

It’s only been 11 innings for Dean Kremer, whose season started late due to injury. He has thrown his splitter dramatically more frequently, and even though it sports just an 87 Stuff+, the pitch has generated an elite 25.7% SwStr%. That pitch is doing the majority of the heavy lifting here. It’s always been a good pitch, but he has thrown it 42.3% of the time so far this year, versus just 21% last year and 18.4% the year before. Upping its usage is clearly a recipe for more whiffs, though perhaps hitters will eventually catch up.

I guess if Roki Sasaki couldn’t increase a lowly 8.7% SwStr% this year, he was going to either find himself in the bullpen or Triple-A. He’s still not striking out the rate of batters we all thought he was capable of and walks continue to be a major issue. I still haven’t started him in my mixed LABR league and I’m not sure what it’s going to take for me to move him into my starting lineup for a week at this point.

Now let’s flip over to the SwStr% decliners.

When we learned that Connelly Early made the Red Sox starting rotation, he quickly became a popular breakout candidate. So far with a sub-3.00 ERA, it looks like he has been making good on his promise. However, it doesn’t look so good underneath the hood. While his Stuff+ is actually slightly higher, every single one of his pitches is generating a lower SwStr% compared to last year’s cup of coffee. Most egregious is a sinker that he has thrown 90 times and only recorded a 1.1% SwStr% with the pitch! Last year, it was at 14.6% on 41 pitches. There was little chance that high a rate on a sinker was sustainable, but a 1.1% mark might be the lowest I have ever seen on any pitch by any pitcher. I would expect his underlying skills to improve a bit, but owners should really test the waters on how high they can sell him right now.

Man, who did Justin Wrobleski make a deal with to post a 1.50 ERA, despite a 5.17 SIERA and microscopic SwStr% and strikeout rates?! Since he moved from the bullpen last year, his velocity is naturally way down, though he did mostly serve as a starter in 2024 and his velocity is well down from then also. I doubt anyone is buying him, but with these underlying rates, I wouldn’t even want him starting for my NL-Only team if I had one.

A 13.1% strikeout rate for Sonny Gray?! I was worried about him after a velocity loss last season that is getting closer to the danger zone, and that velocity has remained this year. Surprisingly, it didn’t affect his strikeout rate last year and his Stuff+ hasn’t been affected either. So I’m not sure what’s behind the lack of whiffs so far. I would be too nervous trying to buy here.

Max Scherzer just hit the IL and you have to wonder if any of those injuries had been impacting his performance so far. I would probably just be happy I don’t have to think about whether to start him for a little while if I were an owner.

After missing much of the 2024 and 2025 seasons to an elbow injury that ultimately required TJ surgery, a healthy Kyle Bradish was a popular sleeper this year. While his SwStr% is well down from last year, it’s actually right in line with every season prior since last year so far looks like the outlier. Control has been an issue, which isn’t surprising coming off elbow surgery. With only a 103 Stuff+ at peak, I wasn’t really a big fan to begin with, so I personally wouldn’t be interested in trying to buy low here.

What happened Bubba Chandler?! Not only has his SwStr% and strikeout rate slipped, but his control has abandoned him. That’s not a good combination. It’s actually pretty crazy to see where those first two rates are sitting considering he has averaged 98.7 MPH with his fastball and sports an overall Stuff+ of 103. Heck, even his Location+ is 102, which actually makes me question if there’s any relationship between that metric and walk rate at all! Even PitchingBot gives him an elite Stuff grade and league average Command. All in all, his underlying skills seemingly should be significantly better. Obviously, it’s hard to project that to actually happen and keep starting him. Perhaps he makes for a good target in a keeper league.

I was going to ask why the Twins keep picking Simeon Woods Richardson over Zebby Matthews, but Matthews himself owns a bloated 5.91 ERA at Triple-A this year, so perhaps he wouldn’t have been much better of a bet. Then again, it’s hard to be any worse than Woods Richardson has been so far. None of his stuff metrics have ever been any good and his walk rate has teetered close to double digits. I can’t imagine he remains in the rotation for much longer.

Kyle Leahy’s appearance here isn’t a surprise considering he moved from the bullpen to the rotation this year. Of course, it’s been quite a disappointing transition, as the underlying skills are poor. There’s no upside here.

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