Starting Pitcher Stuff+ Risers & Fallers – Apr 28 2025

From 2021 to 2024, there has been about a 0.70 correlation between pitcher strikeout rate and Stuff+ grade for those who have recorded at least 100 innings. That’s pretty significant! It means we have a nice proxy for strikeout rate without having to worry as much about sample size, as strikeout rate could fluctuate wildly after over just a couple of games. I would imagine Stuff+ stabilizes much more quickly. So it’s worth monitoring changes in Stuff+ or newly established marks for rookie pitchers to quickly get a rough idea of strikeout potential. So let’s check in on the starting pitchers who have experienced the greatest gains and losses in Stuff+ compared to last year.

2024 breakout Hunter Greene easily leads the pack here with a whopping 14 point gain in Stuff+. He has enjoyed gains across all three of his primaries pitches, including 10 points on his four-seam fastball, four points on his splitter, and an incredible 14 points on his most used secondary, his slider. Each of his pitches has averaged the highest velocity of his career, though his fastball is basically back in line with his 2022 debut mark, as the season average is inflated by an absurd 100 MPH mark during his second start (his second highest game average was 99.3 MPH). This is a nice rebound after he saw a velocity drop last year, which turns around a two-season downtrend. You wouldn’t necessarily think that a guy adding velocity who already averages 97.6 MPH would matter a whole lot, but clearly added velocity matters regardless of the baseline.

The increased velocity has resulted in a spike in SwStk%, which ranks second among qualified pitchers, though his strikeout rate has only merely rebounded after a decline last year, while failing to exceed his 2022 and 2023 marks so far. He has upped his extreme fly ball ways even more this year, as he has posted the second highest FB% among qualified pitchers, which seems pretty scary when pitching half his games in the most favorable home run park in baseball. Finally, he has cut his walk rate by more than half, and it’s anyone’s guess whether that’ll last or how much of the current improvement is sustained. I was out on him given his vast SIERA overperformance last year, but I’m definitely much more optimistic now than I had been heading into the season.

Tylor Megill’s Stuff+ gains have all come from his two fastballs, with a crazy 19 point gain from his four-seamer and seven point gain from his sinker. His most used secondary, his slider, has actually lost six points. Interestingly, his fastball velocity is down slightly compared to last year, but in a normal range this early. I don’t see a whole lot of difference in his fastball spin rates or movement, so I’m not sure what has led to the increased Stuff+ grades. Overall, his SwStk% is down from last year, CSW% is basically average, yet his strikeout rate is at a career high. That’s pretty baffling, as he seems to be sequencing well to post that kind of strikeout rate with mediocre SwStk% and CSW% marks. The Stuff+ gains are exciting, but I’m not seeing anything in his result profile to maintain that excitement.

Of the pitches Hunter Brown throws most frequently, his Stuff+ gains have come from a 13 point gain from his four-seamer, a nine point gain from his sinker, and a 15 point gain from his knuckle curve. His changeup, which he has thrown a bit more often, has lost some Stuff+, taking it from below average already to even further below. Like Greene above, Brown has enjoyed a velocity spike, as every single one of his pitches has averaged the highest velocity of his career. That has led to a jump in SwStk% to his highest mark, driving a strikeout rate surge. Also like Greene, Brown has reduced his walk rate, but over small samples, I’m usually a non-believer of improved control until I see it over a longer period. Brown was already plenty good last year, and this velocity gain should ensure he repeats, at the very least.

As a Rockies starting pitcher, Kyle Freeland has rarely been rosterable, except for his miracle 2018, which no one really believed until the season ended anyway. He has mainly seen Stuff+ gains in his four-seamer and a massive one on his slider. Over his career, he has posted a 4.19 ERA on the road, though surprisingly his strikeout rate has been a bit lower. His velocity hasn’t changed much, but perhaps the improved stuff will make him streamable during away games.

Cristopher Sánchez was the talk of spring training with his velocity surge, especially given that he already owned control and groundball inducing skills. All he needed was the strikeout rate to potentially move into the elite, and the velocity spike had us dreaming that might happen now. His changeup was already strong, though he has enjoyed a small increase in Stuff+ on the pitch, but he has enjoyed even bigger gains on his sinker and slider. Now all three of his pitches sit with Stuff+ grades between 114 and 116! So far, everything we had hoped his velocity spike would bring has. Unfortunately, he left his last start with forearm soreness, which was paired with his worst velocity of the year. It was an ominous sign, but the early word is that he is okay and perhaps he won’t even hit the IL. We’ll see if his velocity rebounds next start.

Freddy Peralta’s Stuff+ gain is primarily driven by a 14 point increase in his four-seamer, with smaller increases in his slider and curveball. Like a number of names above, Peralta has experienced a velocity spike, with all his pitches sitting at career best velocities. Peralta’s ascent has been pretty incredible, as he debuted in 2018 averaging just 90.7 MPH with his fastball. So far this season, he’s been sitting at 95.1 MPH, which is a crazy 4.4 MPH increase throughout his career! The increased velocity has led to high highest SwStk% since the short 2020 season, though a lack of called strikes as resulted in his third lowest CSW% and the lowest strikeout rate of his career. I’m guessing the strikeout rate will tick up over the rest of the season, especially if he maintains the higher velocity.

Tarik Skubal has enjoyed small Stuff+ increases across the board, with the exception of his four-seamer, which has seen a gaudier 11 point increase. Incredibly, now every one of his pitches, excluding his rarely used knuckle curve, stands with a Stuff+ mark of at least 112. That has led to a career best 15.4% SwStk%, though oddly his strikeout rate is well down by 5.3% versus last season. His velocity, which first spiked in 2023 and increased again last year, is once again higher on every one of his pitches. How much higher can he go?! So everything looks fantastic here, which makes it even more head-scratching to see just a 25% strikeout rate. That’s going to rise, without a doubt.

Gosh, Taijuan Walker is still around?! He appears on this list mostly because last year was the worst Stuff+ mark of his career, so this is really just a rebound closer to historical levels. That said, both his least thrown pitches, his four-seamer, and curveball, have experienced the biggest surges in Stuff+ to career bests. His velocity is a bit higher than last year’s career low, but remains well down from his past. I wouldn’t touch him in any league format as I’d prefer a middle reliever in an NL-Only to protect my ratios.

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

Wow, this is quite a fall for José Soriano, who overperformed his SIERA and xERA last year, and made it onto many sleeper lists this year thanks to his combination of velocity and GB%. His Stuff+ decline is mainly fueled by a drive from his sinker of 14 points and even larger drop of 29 points from his knuckle curve. Those declines are partially offset by a jump of 18 points in his slider. That’s a lot of changes in his stuff! His sinker has lost 1.1 MPH, while his slider is down a huge four miles per hour and knuckle curve down 1.7 MPH. Those velocity declines barely affected his SwStk% so far, which is nearly identical to last year, and while his CSW% is up a bit, his strikeout rate has fallen into territory rarely associated with a rosterable asset. Since his control continues to underwhelm, the strikeout rate decline is hard to swallow. At least the grounders are still there, which gives me hope that eventually he could turn into Framber Valdez, but right now, you need blind optimism.

Oy vey, this has not been the start that I, as a Yusei Kikuchi owner, wanted. He has lost Stuff+ on all his pitches, notably a 14 point drop from his four-seamer and 13 point drop from his slider. Those are his two most thrown pitches! His fastball velocity is at its lowest since his 2019 debut, before he enjoyed a spike in 2020 that has been sustained since. He clearly needs that velocity, as his strikeout rate was sub-20% back in 2019 and is right at 20% now with the reduced velocity. His control has also taken a downturn, as batters are swinging far less at his pitches outside the strike zone, bumping up his walk rate. All we can do right now is hope the velocity returns.

Yes, some of Corbin Burnes’ other pitches have lost Stuff+, but it’s all about his cutter. The pitch’s Stuff+ sits at a league average 100, dipping 11 points compared to last year and down 18 points from its career average. Its velocity is down 1.2 MPH compared to last year, and its lowest since he started throwing it frequently back in 2020. Without an elite cutter, his SwStk% has collapsed into single digits for the first time, while his strikeout rate has continued its downtrend, which has now declined for a fifth straight season. Oh, and his walk rate has popped into double digits for his highest career mark. I still assume that his name value exceeds his projected future value meaning he probably wouldn’t make a good trade target, and all owners could hope now is that the cutter returns.

Aaron Nola came into spring training with lower velocity and that has continued throughout the regular season. That has hurt the Stuff+ of every single one of his pitches, though most affected has been his most used pitch, his knuckle curve, with a 12 point loss in Stuff+. At age 32, it’s not crazy to believe the velocity isn’t coming back, but I feel like it’s still too early to be confident it’ll remain down all season. He has still managed to post strong underlying skills though, as evidenced by his 3.55 SIERA, though his 4.66 xERA suggests that some of his inflated BABIP and HR/FB rate are deserved. He would have to come at a major discount compared to his draft day cost for me to trade for him, but if his velocity does return, I would certainly be buying.

Andre Pallante also dealt with velocity loss during spring training and that has carried over to the regular season. He has mainly seen a Stuff+ loss from that four-seamer, and he doesn’t exactly have the secondaries to handle a loss of fastball velocity. Surprisingly, his SwStk% is easily sitting at a career high, but the strikeout rate remains as weak as ever. I love the high GB%, but that’s all he’s got.

Martín Pérez is likely out for the season.

Brandon Pfaadt seemed like an obvious sleeper after vastly underperforming both his SIERA and xERA last year. But his stuff has degraded this season, mostly due to his four-seamer, sinker, and slider. Oddly, his most used secondary has been his changeup, which has sported the lowest Stuff+ of all his pitches every single year, including this one. Why on Earth would he throw his worst pitch the most?! His four-seam fastball and sinker velocities are down slightly, but not by anything to worry about, while his SwStk% and CStr% have declined, bringing his strikeout rate down. The ERA looks great though thanks to great BABIP and LOB% fortune, partially offset by gopheritis, but that won’t last. I would probably just hold him and hope the Stuff+ grades rebound.