Last season featured many breakout pitching performances in fantasy baseball from players like Mitch Keller and Jesús Luzardo, but before their breakout in 2023 we saw them make big gains in Stuff+ the previous season.
Biggest Stuff+ Gainers of 2023
What is Stuff+?
Put shortly, Stuff+ measures the “nastiness” of a pitcher based on the physical traits of their pitches, summarizing a pitcher’s speed, movement, and how well the pitches “play off each other” in a nice tidy number.
Why does it matter?
Stuff+ highly correlates with a pitcher’s ability to generate swings and misses, a skill that has become a north star when predicting a player’s future performance.
With that said, here are the starting pitchers that saw significant Stuff+ gains in 2023 to keep an eye on as we approach the 2024 fantasy baseball draft season.
Graham Ashcraft, CIN
2022 Stuff+ 109, 2023 Stuff+ 128
Looking at all starters with +60 innings pitched last year, who would you guess had the highest Stuff+ in all of baseball (aka the “nastiest” starter)? Spencer Strider? Dylan Cease? Shohei Ohtani? No, it was Graham Ashcraft.
On the surface, it was a repeat of a mediocre season for Ashcraft, who posted a 4.76 ERA in 145.2 IP after having a 4.89 ERA in 105.0 IP his rookie season. However, his two best pitches saw increases in Stuff+, with his cutter Stuff+ increasing from 113 to 117, and his slider from 123 to 166 (the second highest slider Stuff+ among starters).
Graham Ashcraft, White Castle Special with a Side of Sword. 🤮🍔🍔🍔⚔️ pic.twitter.com/vSxL9CLyff
— Rob Friedman (@PitchingNinja) September 1, 2023
A toe injury ended Ashcraft’s season early in 2023, but the 2024 Reds will be counting on Ashcraft, who is entering his Age-26 third season as the projected #2 starter.
Kyle Bradish, BAL
2022 Stuff+ 108, 2023 Stuff + 126
In addition to being a Stuff+ Gainer, Kyle Bradish had both a fantasy and major league breakout season in 2023, finishing fourth in AL Cy Young voting ahead of Luis Castillo, and helping Baltimore capture its first division title in 9 seasons.
Kyle Bradish featured an above slider in 2022 (124 Stuff+), but in 2023 his slider had the highest Stuff+ in all of baseball (ahead of Graham Ashcraft) at 171. Bradish also saw increases in his velocity as the year went along; his fastball, sinker, slider, and curveball were all averaging 1-2 mph faster in September than they were in April.
Kyle Bradish, K'ing the Side. pic.twitter.com/zrdXvCZJXX
— Rob Friedman (@PitchingNinja) August 20, 2023
Bradish sits as the proven ace of the Baltimore Orioles and likely will be named the Opening Day starter (barring an unlikely major FA signing). Stuff+ says his breakout performance in 2023 was no fluke.
Nick Pivetta, BOS
2022 Stuff+ 107, 2023 Stuff+ 118
Here are some ranks for Nick Pivetta’s 2023 season among the 102 pitchers with +120 innings:
- ERA: 4.04 (53rd)
- K%-BB%: 22.7% (8th)
- SIERA: 3.36 (6th)
So Pivetta did not deliver the season we hoped for but did so while posting elite underlying numbers. In 2023 Nick Pivetta had an increase in Stuff+ that seemed to stem from an increase in velocity (avg. fastball was 1.0 MPH faster), and increased usage of his slider (from 2.8% in 2022 to 11.1% in 2023).
Nick Pivetta's 13Ks in Relief (Red Sox Record) pic.twitter.com/r0LhU6jScE
— Rob Friedman (@PitchingNinja) July 18, 2023
The main concern for Pivetta will be role more than effectiveness. This past season he was used as a swingman starting the season in the rotation, transitioning to a relief role by May before moving back to starter in September. Going into 2024 he is projected to be Boston’s No. 2 starter behind Chris Sale.