With the 2025 season wrapping up, we can begin to look back on the past five-plus months of minor league games and draw some conclusions. The sample size of data available is now standardized, allowing us to view certain metrics with a greater degree of confidence.
One such piece of data is our internal Stuff+ metric, for which we access the full suite of minor league data via sourcing and apply our proprietary formula developed by Dylan White. For today’s deep dive, we’ll be using normalized versions of these Stuff+ scores to identify some sleeper pitching prospects who popped up this season and are worth paying attention to.
We normalize our Stuff+ score results by rebalancing the data of each pitch classification against the average Stuff+ for that pitch type. In other words, because the average slider has a Stuff+ of 110, if a pitcher has a slider with a Stuff+ of 110, it is considered an “average” example of such a pitch and would therefore be rebalanced to 100 on the normalized scale. The weighted average of each pitcher’s normalized arsenal then results in their normalized Stuff+ score.
Using this model allows us to more accurately identify which pitchers are bringing elite stuff to each at-bat. And to increase our chances for identifying starters, we made sure each of the nine players included below threw a minimum of 900 pitches in the minors this season.
With all that in mind, let’s take a look at some arms who stood out as potential sleeper picks.
Christian Oppor, LHP, White Sox
The 2025 season was a big one for Oppor, as the lefthander spent all of 2024 on the complex before making his full-season debut this year.
Oppor mixes three above-average pitches, per Stuff+. His four-seam fastball sits in the mid 90s, and he mixes a changeup with good velocity and vertical separation off the heater. Oppor’s low-80s sweeper registers the highest of any pitch in his arsenal and also boasts the highest whiff rate.
Oppor was a true breakout performer for the White Sox this season.
Gerelmi Maldonado, RHP, Giants
Signed out of Venezuela in January 2021, Maldonado had Tommy John surgery in December 2023 and returned to action in 2025. Over 23 appearances this season spanning 59 innings, Maldonado flashed some of the best stuff in the minors.
At present, Maldonado works with a limited arsenal of only two pitches, hinting at a likely relief role long term. His four-seam fastball sits 97-98 mph, touching 101.3 mph at peak, while his slider is a sweeper at 83-85 mph with about a foot of sweep on average.
Wilber Dotel, RHP, Pirates
A 2020 international signing out of the Dominican Republic, Dotel has spent a season per level the last three years. In 2025, he made 26 starts for Double-A Altoona, pitching to a 3.88 FIP while showing swing-and-miss stuff and command.
Stuff-wise, Dotel has a plus arsenal featuring a mid-to-high-90s fastball, a mid-80s cut-slider and a splitter. All of his pitches rate as plus per Stuff+, and each drive above-average whiff rates and results.
Levi Wells, RHP, Orioles
Drafted by the Orioles in the fourth round in 2023 out of Texas State, Wells boasts arguably the best stuff in the system. He mixes four pitches—a mid-90s four-seam fastball, low-80s two-plane curveball, a mid-80s sweeper and a low-90s cutter—each of which grade out as plus, per our Stuff+ model.
With the potential for four plus pitches, Wells might be one of the more underrated starters in the minors.
Will Watson, RHP, Mets
Normalized Stuff+: 115
Mets pitching development has been on fire of late, as New York seems to be churning out quality arms at a rate not seen since the organization’s World Series heyday ten years ago. Looking beyond their most recent crop of current major leaguers in Nolan McLean, Jonah Tong and Brandon Sproat, there are still some talented arms lurking in the minors.
One such pitcher is Watson. Drafted out of USC in the seventh round in 2024, the 22-year-old righty has enjoyed a breakout season for the Mets. He has a plus offering in his four-seam fastball and two above-average pitches in his slider and cutter.
Watson shows a deep arsenal of quality offerings and enough command to stick in a starter’s role long term.
Antwone Kelly, RHP, Pirates
Like his org mate, Wilber Dotel, Kelly was a notable climber in our midseason Top 30 prospect lists update.Signed by the Pirates in January 2021 out of Aruba, he enjoyed a very strong 2025 campaign, as he split the season between High-A Greensboro and Double-A Altoona. Kelly mixes three pitches, but the majority of his usage comes from his plus fastball.
PlayerVeloMax. VeloSpinIVBHBVAAEXTBubba Chandler97.7 mph101.7 mph2453 rpm17.9 in.8.2 in.-4.446.64 ft.Antwone Kelly97 mph100.7 mph2375 rpm16.3 in.8.7 in.-4.476.3 ft.
As you can see from the metrics above, Kelly’s fastball compares favorably to Pirates top pitching prospect Bubba Chandler. Chandler’s fastball performed better this season than Kelly’s, but the similarities are striking.
Kelly also features two above-average secondaries that show bat-missing ability in his mid-to-high-80s cut-slider and a changeup with significant vertical separation off his fastball. Kelly is another sneaky name to watch in a Pirates system that has been improving over the last few years.
Jefferson Jean, RHP, Athletics
After profiling a handful of pitchers who flashed great stuff and good results, let’s now introduce you to the wild card of the bunch.
Despite excellent stuff, Jean has struggled with command to such a degree that his results have been well below the level of acceptability. Even so, the 20-year-old righthander is intriguing.
Jean mixes a sinker at 93-95 mph featuring an average 16-18 inches of armside run, a low-80s slider with ride and sweep and a high-80s changeup. He has plenty of time to figure it out, making him a great name to follow in the coming years if the command improves.
Keythel Key, RHP, Angels
Key is, admittedly, probably a name few are discussing this season, as he posted a 5.13 ERA with High-A Tri-City. However, despite not producing at the level his stuff would suggest, Key is worth your attention.
In consecutive seasons, Key has shown the ability to handle innings (194 IP between 2024 and 2025) to go with plus stuff across his arsenal. He mixes a mid-to-high-90s fastball with a low-80s sweeper featuring two-plane break and an upper-80s changeup that shows elite vertical separation off of his fastball. Command across his arsenal is below-average, but his zone rates hint at long-term upside.
Likely a reliever down the line, Key’s elite stuff is worth monitoring.
Brooks Auger, RHP, Dodgers
Every season the Dodgers pluck a player from relative obscurity from the draft and then watch as that player becomes a standout the following season. While I’m not sure Auger has quite reached standout status yet, the 2024 sixth-round pick flashed interesting traits in his professional debut.
Primarily a reliever at Mississippi State, Auger took to starting in 2025, making 17 starts spanning 91.1 innings. Despite a 5.12 ERA and below-average swing-and-miss rates, Auger has my attention.
He generates four distinct pitch shapes in his four-seam fastball, slider, cutter and changeup. The fastball and cutter are his bread and butter, and the stuff is good enough to project better days ahead.
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