Starting Pitcher Stuff+ Gainers & Decliners — April 21, 2026

From 2021 to 2025 among pitchers with at least 100 innings recorded, Stuff+ has a 0.708 correlation with strikeout rate. That’s quite significant. Although I don’t have the stabilization point of Stuff+, I have to imagine it becomes meaningful far more quickly than strikeout rate. Assuming that’s the case, it follows that monitoring Stuff+ changes is key to predicting future strikeout rate direction.

Let’s now dive into the starting pitcher Stuff+ gainers and decliners, beginning with the former.

Who had Emerson Hancock as the early biggest Stuff+ gainer on their bingo card back in January?! He has totally changed his pitch mix, throwing his four-seamer and slider more, adding a cutter, and reducing his sinker and changeup usage. Despite not gaining any velocity, his four-seam Stuff+ has jumped, while his slider has spiked as well, even though it has actually lost meaningful velocity. Even more odd is that he has posted a robust 29.4% strikeout rate, but just a 24.1% CSW%, the same as last year when his strikeout rate sat at just 16.6%! So I have no idea what’s going on here. His Stuff+ suggests a dramatically better CSW%, and higher SwStr%, but given those current marks, his strikeout rate looks like a complete fluke. Something has to give, with either the SwStr% and CSW% surging, his strikeout rate collapsing, or the two meeting somewhere in the middle. But both cannot stay where they currently are.

Jake Irvin has changed his pitch mix a bit, and while his velocity is up from last year, that was solely because it had dropped, and is still well below his 2023 and 2024 seasons. His Stuff+ is now barely above league average, but it has been enough to result in a career best strikeout rate, SwStr% and CSW%. His control has disappeared though and he’s become an extreme fly ball pitcher, so I’m not exactly enthused here.

Gee golly, Roki Sasaki’s stuff has improved, but it’s still below league average! And of course, he continues to walk the farm. I’m so afraid to drop him in the one league I own him (he has remained on my bench all season), but I don’t intend to start him anytime soon.

It might be tempting to use the Stuff+ gain to confirm this is the Taj Bradley breakout, but this is merely a rebound back to his 2023 and 2024 marks. That’s still a good thing, as his strikeout rates were closer to 30% those years, so he’s clearly got the strikeouts back. But since his CStr% remains middling, his CSW% is just barely above average, which calls into question the sustainability of that high strikeout rate. Ominously, his fastball velocity has declined in every start, so his season mark is now the same as it’s always been, as opposed to higher. I still think he has breakout potential, but really only because he has constantly underperformed his SIERA/xERA, so better fortune is all he actually needed. But I liked him better when his season velocity was over 97 MPH.

Janson Junk’s Stuff+ and velocity increase hasn’t done a thing for his strikeout rate and he hasn’t maintained his miniscule walk rate from last year. He isn’t generating swings and misses or called strikes, so I have personally lost the interest I had in him.

Pretty impressive that Jesús Luzardo appears here when he was already above average last year. The skills here are elite, though some of that .417 BABIP is justified given the ridiculous 29% LD% and zero pop-ups induced. He’s seemingly the ultimate buy low if any of his owners are too focused on that inflated ERA.

A strong spring training made Matthew Liberatore a popular sleeper and his Stuff+ is back above league average. However, neither has translated to the regular season, as his strikeout rate is tiny and his SwStk% is actually down. He has massively overperformed his SIERA/xERA, so I wouldn’t want him active in any leagues right now, even if that strikeout rate should come up.

Over a smaller sample, Javier Assad has finally gotten his Stuff+ up to league average. He has so far made a career of massively overperforming his SIERA/xERA, so you’ll have to decide whether you want to bet on that happening once again. I wouldn’t, as I’m always going to bet on the skills and if an overperformer slips through the cracks and produces for another fantasy team, so be it.

Kodai Senga’s early velocity spike was short-lived, as his marks his last two starts matched where he sat back in 2023, before a decline last year. He also got blasted in those outings, so it’s fair to wonder which version we’re going to be getting the rest of the way. Interestingly, his best start by Stuff+ was two starts ago, and his worst start by Stuff+ was his last one. So he doesn’t necessarily need the big velocity spike we saw in his first start for his stuff to grade out well. I’m sticking with him, but we’ll see if his velocity trends any lower.

Weird how down Framber Valdez’s strikeout rate was before last outing with such strong Stuff+ marks, though I’d say his strikeout rate has generally underperformed his Stuff+ marks throughout his career. For whatever reason, his stuff just hasn’t produced as many swinging strikes this year. As an owner, I’m not worried, I think he’ll be fine.

Gavin Williams’ velocity has been stable, but he did change his pitch mix a bit and now his Stuff+ is sitting at a career high. It has resulted in a big strikeout rate surge, backed by strong SwStr% and CSW% marks. I wouldn’t count on his strikeout rate staying this high, but a career best should be in the cards. The concern, though, is a skyrocketing walk rate, which was problematic last year to begin with.

Don’t get too excited about the Stuff+ gains for Germán Márquez, as it remains well below league average and merely brings him back to where he was in 2024. He goes from an automatic avoid because of Coors Field to an automatic avoid because his skills remain weak.

Luis Castillo’s Stuff+ has rebounded after last year’s sub-100 mark, but still sits well short of his peak years. He stopped his velocity decline, and yet his strikeout rate, SwStr%, and CSW% all sit at career worsts. It’s truly time to look past the name and focus on the skills here, as those strikeouts we became accustomed to are not coming back.

Dustin May’s Stuff+ remains a far cry from his elite years before last season, as injuries have really taken a toll. He isn’t missing any bats despite the better than average Stuff+, so it’s really difficult to predict his future.

Randy Vásquez was the talk of the town when he was showing increased velocity during spring training. It has partially stuck during the regular season, but it hasn’t been as dramatic a gain. Even with the increase, his Stuff+ remains below league average and below his 2023 and 2024 marks. With a below average Stuff+, I’m wondering how he has managed such a strong strikeout rate and SwStr%. I’m not betting on that to continue, but he’s clearly an improved pitcher. My bold prediction is looking good!

Now let’s flip over to the Stuff+ decliners.

It was only one start for Merrill Kelly, so I won’t read too much into it. His Stuff+ has always been weak, so you just have to hope his Location+ finishes above average like usual.

Michael McGreevy’s velocity is down nearly two miles per hour, his Stuff+ is the lowest among 74 qualified pitchers, and his SwStr% sits at just 5.2%. Yet, his ERA is a sparkling 2.49! If his velocity doesn’t improve, he’s one of the more obvious imminent implosion candidates.

There have been lots of concerns shared about Emmet Sheehan, whose velocity did bounce up in his second to last start, but was down again in his last start. He has still managed to post a 13.1% SwStr% and above average CSW%, so even if the velocity doesn’t improve, that strikeout rate should be higher. I’m actually surprised his Stuff+ wasn’t higher last year given the elite SwStr% and and strikeout rate. I’m eager to see where his velocity is next start.

After a career best Stuff+ last year, Edward Cabrera’s mark now sits at a career worst. Isn’t it funny how that happens? His fastball velocity is down a bit and his strikeout rate is shockingly sitting below 20%. Oh, and the walks are back. Yet some how, some way, his ERA sits at just 2.38. He could potentially be a sell high to someone not paying attention to the peripherals and believing this is confirmation last year’s breakout was real.

Wow, not only is Jacob Lopez’s Stuff+ down, but he has walked more than he has struck out! He’s unplayable.

Reynaldo López’s velocity remains well down and rather than gradually improving, he recorded his worst average in his last start. His strikeout rate and SwStr% are also down dramatically from his surprise 2024. But like some of the other names above, you wouldn’t know any of this based on his 2.18 ERA! Regression is coming.

It should be pretty big news when Paul Skenes’ Stuff+ is barely above league average. His velocity is down nearly a mile per hour, but you would think that 97.3 MPH should still be plenty good enough to keep his Stuff+ higher. His strikeout rate, SwStr%, and CSW% are all non-Skenes like and his ERA sits at unfamiliar perch above 3.00 for the first time. There’s nothing a Skenes owner can really do, other than be reminded how hard it is to remain the top pitcher year in and year out.

Tomoyuki Sugano is not cut out to be a Rockies pitcher given his low strikeout rate. Luckily, he’s posted just a 2.53 on the road so far this year, so his season hasn’t looked so terrible. It likely won’t take much longer for that to change.

Man, am I glad that someone else liked Cole Ragans more than me in all my leagues. What on Earth has happened here?! His velocity has been down all season and it was at a season low last start, leading to a career low strikeout rate and SwStr%…by far. Oh, and he’s walked 19.6% of opposing batters (he and Jack Flaherty may want to get together to discuss their sudden bout of the yips). I have no idea what’s going on here, but you have to wonder if he’s completely healthy.

Both Kyle Leahy and Reid Detmers have transitioned from relief, so it makes sense that their Stuff+ marks have suffered.

If you heard that Dean Kremer had posted a 37.2% strikeout rate and 14.2% SwStr% in his first two starts, you would assume his velocity must have spiked and his Stuff+ surged. Nope! He did change his pitch mix, doubling his splitter usage, but that pitch actually sports just an 86 Stuff+. I don’t know how he has recorded so many swings and misses, along with those strikeouts, but either Stuff+ is reallllllly missing something, or his strikeout rate is going to drop right back to where it’s always been.

Andrew Abbott was an obvious ERA correction candidate this year, but that assumed similar quality of stuff. His slider remains strong (albeit down in Stuff+), but everything else is well below average and worse than last year. It’s weird that a guy who posted consistently sky high strikeout rates in the minors of no less than 30.8% has seen his strikeouts disappear after a promising rookie year with a 26.1% mark.

Wait, first Skenes and now Tarik Skubal is suffering a Stuff+ drop too?! Of course, 116 is nothing to sneeze at and ranks fourth among qualified starters. It’s also his second highest career mark, as it’s coming off a career best last year that would be difficult for any pitcher to sustain. He’s the best pitcher in baseball without a doubt.

For the full list of Stuff+ gainers and decliners, plus a plethora of additional metrics for both pitchers and batters updated weekly, visit ProjectingX.com to learn more about and subscribe to ProjectingX IQ.