Starting Pitcher Stuff+, Injury Returnees & Rookies — Apr 29, 2025

Yesterday, I reviewed the starting pitcher risers and fallers in the Stuff+ metric compared to last season. Those lists are super insightful in highlighting pitchers who have seen improvements and declines in the quality of their pitch repertoires. However, a number of pitchers failed to meet my minimum innings requirement last season and were therefore not compared. So today, let’s review 10 pitchers that missed my list due to injury last year or are rookies this season. We can compare the injury returnees to their 2023 numbers and evaluate the rookie marks on their own.

Dustin May missed the entire 2024 season recovering from TJ surgery and then another surgery to repair an esophageal tear. He has pitched parts of six seasons and yet has recorded just 213.2 innings over his career in 38 starts and 50 appearances. During those partial seasons, his Stuff+ never fell below 117, which is pretty amazing. But this season so far, he’s at just 95. Both his fastballs, the four-seamer and sinker, have lost considerable Stuff+ marks, with his four-seamer down 29 points. He has a newly classified slider, coming in at 101 and that’s his highest Stuff+ pitch. His fastball velocity is also down significantly, and it’s declined each season since 2020. None of the declines have affected his SwStk% or strikeout rate, as he’s never been very good at inducing whiffs or generating strikeouts anyway. It’s hard not to fall in love with the potential here, but a skills-based breakout is further away now given the degradation of his stuff.

Jacob deGrom missed the majority of both the 2023 and 2024 seasons also recovering from TJ surgery. Incredibly, he had posted Stuff+ marks between 119 and 124 from 2020 to 2023, then saw a slight decline when he returned last year to 116. This year, he’s all the way down at 106, which is still above average, but nowhere near the elite level we’re used to from him. His marks are down across the board, with the biggest drop coming from his fastball, down from 121/115 in 2023/2024 to just 103 this season. His velocity is down a bit from last year and from the 98+ during his peak seasons, but still well above the league average. He has still generated a strong SwStk% and CSW% to suggest that strikeout rate should rise from here, even if there’s little to no chance he gets above 30% again. He hasn’t thrown more than 92 innings since 2019, so you never know how long you’ll have him for, but he should remain a strong pitcher, albeit not quite at the level we got used to from him.

Kodai Senga made just one start last year as he deal with multiple injuries. This season, he has lost Stuff+ on all his pitches, most notably his forkball, which has gone from a 126 to 113. His fastball velocity is down a bit, but not significantly so to be too concerning. His SwStk% is almost identical to his mark in 2023, but his strikeout rate has plummeted anyway. Since he doesn’t possess above average control and isn’t on one extreme of the batted ball profile spectrum, he really needs those strikeouts. Luckily, good fortune across the luck metrics has saved him so far, but I’m less optimistic now than I was at the beginning of the season.

Sandy Alcantara is yet another TJ surgery returnee, having missed the entire 2024 season to recover. Unlike the other names we’ve discussed so far, Alcantara’s Stuff+ is nearly identical to what it has always been. In fact, he had posted exactly a 110 Stuff+ from 2021 to 2023 and is nearly right there at 109 so far. Talk about consistency! There’s some flip-flopping going on with some pitches seeing increases and others decreases in Stuff+, but everything right now has been above average, sporting marks of at least 101. His velocity is down slightly, but nothing alarming. Unfortunately, despite no degradation in stuff, his SwStk% is down, and his strikeout rate sits at a career low. His walk rate has spiked as well, so the control might be slower to return. His Location+ has taken a nosedive as well, confirming the lack of control. I think we’ll see the strikeout rate rise, though it’s anyone’s guess when his control returns.

Tyler Mahle also missed most of the 2023 season and the majority of the 2024 season recovering from that same TJ surgery, and then later shoulder issues. His Stuff+ has rebounded off a low last year, but it’s still down a bit from his 2021-2023 marks. Overall, he’s always possessed below average stuff, but it’s been his excellent Location+ that has carried him. His fastball velocity is down a bit from previous years, though does represent a small rebound from his bottom last year. His strikeout rate is well down from his peak years, while his walk rate is back into double digits, resulting in a mediocre skill set. Fortunately, he’s killed it with the luck trio, allowing him to handily overperform both his SIERA and xERA. That good fortune figures to run out at some point, and he doesn’t have the strikeout rate cushion to continue providing value when the hits start to fall and home runs start to add up.

The Tigers top prospect and ninth ranked man overall, Jackson Jobe’s debut has been highly anticipated after being selected third overall during the 2021 draft. He owns an excellent 112 Stuff+, which would rank tied for fourth overall if he qualified for the leaderboard. His highest ranked pitch is his most used secondary, his slider, as it sits with a 115 Stuff+. This looks like the repertoire of a future ace, especially considering his fastball averaged 96.6 MPH. Except that this same pitch mix has struggled to earn whiffs. His SwStk% sits at a below average 8.8%, driving just a 17.1% strikeout rate, which is just shocking given the seeming quality of his stuff. Either there’s something missing from the Stuff+ formula that would explain his lack of dominance, or he has endured poor sequencing luck and the strikeouts will come. The latter seems unlikely though considering the underwhelming SwStk%. Given the foundation here, I would have to imagine the strikeouts do eventually come, but it’s anyone’s guess whether that’s this year or in several years.

Kumar Rocker was last ranked as the 75th best prospect in baseball with a killer 80 grade on his slider. Yet, the pitch’s Stuff+ mark sat at just 98 so far this season, meaning all of his pitches were below average. That’s real surprising given his velocity (95.4 MPH) and scouting grades. Though, that velocity is well below the 98.1 MPH he average at Triple-A last year. He recently hit the IL with a shoulder issue, so that may have been bothering him this whole time and affected both his Stuff+ and whiff ability. We have very little history here given his injury-riddled past, but I’m definitely intrigued with his future. It just might take a while to fulfill expectations.

Roki Sasaki leads our prospect list, even though he already had a career in Japan. With an 80 grade splitter and a mid-to-high 90s fastball, it’s clear why he was so hyped. But man it’s been a bizarre beginning to his MLB career. That splitter has certainly been good, coming in at a 114 Stuff+. However, his fastball has been awful at just a 79 Stuff+, which seems really hard to do at that velocity. Even his slider sits at just a 90 Stuff+. How on Earth does this type of prospect end up with just a 91 Stuff+?! A Location+ of 89 confirms he has struggled with his control too, though his 16.4% walk rate could have told you the same thing. You have to assume that he’ll improve at some point, but he has been disappointing so far. It’s been quite the magic act to record a 3.55 ERA with those peripherals!

Shane Smith has been one of the few White Sox bright spots so far this season. Unfortunately, his Stuff+ has been underwhelming, as both his fastball and slider sit at 90 marks, while his changeup is his only above average offering at 102. Even with the seemingly below average stuff, he’s generated an above average SwStk%, though with a low CStr%, he has posted a below average strikeout rate barely above 20%. Like some of the others on these lists, he has ridden a great heaping of good fortune to a sub-3.00 ERA, though both ERA estimators confirm he’s still worth rostering.

It’s not often you see a 35-year-old come over from a foreign league, but that’s exactly what Tomoyuki Sugano did when he came over from Japan. The stuff here ain’t very good, though he does throw the kitchen sink, recording six different pitches, all thrown at least 13% of the time. His only above average pitch has been his slider, coming in at a 107 Stuff+, and that’s his second most thrown offering. His four-seamer clocks in at a 98, while the rest of his pitches are all below 90, with his splitter, his most thrown pitch, all the way down at 74. The lack of stuff has resulted in a low 7% SwStk% and microscopic 8% strikeout rate, which seems impossible to pitch a whole season with. His ERA estimators warn of an implosion coming as his BABIP appears unsustainably low, and there’s little chance he continues stranding runners at his current pace.