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Corbin Young's deep dive into four fantasy baseball starting pitchers to decide if their surprisingly good form merits a roster spot or staying on the waiver wire for Week 12 (2025).
Welcome back to Unlikely Aces. We're heading into late June, with students heading into summer break, meaning the heart of the fantasy baseball season. It's fun to stream starting pitchers and find success. However, sometimes streaming pitchers can destroy the ratios. We should have a process for any waiver wire move, start/sit decision, or player examination.
Some pitchers possess high-end skills but don't perform well. Meanwhile, we have situations where pitchers perform well while lacking above-average skills, and we must decide whether that's sustainable or not. We'll examine four starting pitchers who have been performing well lately and whether their underlying metrics suggest some sustainability.
Are these unlikely aces for real, or is it safe to leave them out on the waiver wire with negative regression surely coming? Let's take a deeper look!
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David Peterson, New York Mets
76% Rostered in Yahoo Leagues
One quick way to check if a pitcher is legitimate is to examine their xERA, K-BB percentage, and swinging strike rate. Peterson's xERA is 3.30, nearly one run higher than his actual ERA (2.49). Meanwhile, Peterson's 13 percent K-BB percentage and 10.7 percent swinging strike rate don't indicate above-average strikeout skills.
However, it's worth noting Peterson boasts a 12 percent swinging strike rate in May with 12.7 percent in June, giving us slightly more confidence if he maintains the whiffs. Peterson's slider has been feasting, with a 19.9 percent swinging strike rate in 2025, leading his arsenal and close to his career average (20.7 percent). The batted ball results against the slider against left-handed hitters (.105 wOBA, .144 xwOBA) have been better than his outcomes against right-handed hitters (.273 wOBA, .264 xwOBA).
However, Peterson's batted ball outcomes have improved against the slider for both sides of the plate in 2025. Besides Peterson's slider, one might wonder what else he brings to the table with his arsenal. Peterson's changeup (11.3 percent) and curveball (11.9 percent) typically were the two other decent offerings in swinging strike rates.
However, Peterson's changeup has been his only other effective pitch that he throws to right-handed hitters. Fantasy managers should value Peterson as a streamer with minimal strikeout upside.
Grant Holmes, Atlanta Braves
57% Rostered in Yahoo Leagues
Holmes saw Spencer Strider cook in his most recent outing and said, "Watch this." He set a career-high in strikeouts (15) and whiffs (25) over the weekend against the Rockies.
For context, Holmes rocks a 3.40 xERA (3.97 ERA), 17 percent K-BB percentage, and a 13.1 percent swinging strike rate in 2025. Holmes has a similar xERA to 2024 (3.65), yet his K-BB percentage (19 percent) and swinging strike rate (16.5 percent) fell from the 2025 numbers.
Holmes' slider (23.5 percent) and curveball (22.5 percent) swinging strike rates were dominant in 2024. However, he maintained the slider whiffs (21.7 percent), yet saw his curveball whiffs disappear to a 14.8 percent swinging strike rate in 2025. Holmes' slider added three inches of downward movement, theoretically leading to more whiffs and weak contact. Meanwhile, Holmes' curveball gained three inches of drop and an inch of glove-side sweep.
Holmes throws his curveball most often against left-handed hitters (24.6 percent), leading to quality results. That's evident in Holmes' curveball wOBA being .258 (.224 xwOBA) against left-handed hitters in 2025. Meanwhile, Holmes consolidated his approach to right-handed hitters, with sliders (44.1 percent) and four-seamers (40.2 percent). He threw more sliders and four-seamers toward right-handed hitters in 2025 while lowering the cutter and curveball usage.
If fantasy managers can buy Holmes, it's a good time to do so. However, Holmes' fantasy value likely went up after a career-type performance against the Rockies on the road. Holmes possesses the skills we typically want to buy into, as a high-end pitcher with strikeout upside.
Jeffrey Springs, Athletics
32% Rostered in Yahoo Leagues
After a rough April (7.66 ERA, 6.54 xERA), Springs improved his ratios, with a 3.58 ERA in May (5.13 xERA) and a 3.86 ERA in June (3.34 xERA). As we mentioned earlier, one way to examine a pitcher's skills and legitimacy involves checking the season-long xERA, K-BB percentage, and swinging strike rate. Springs has been like himself of old, with a 4.72 xERA, 10 percent K-BB percentage, and 11.6 percent swinging strike rate.
The changeup for Springs has been deadly, with a 24.5 percent swinging strike rate in 2025, similar to his career norm. Besides the changeup, Springs lacks any other offering with a swinging strike rate in the double digits. That makes Springs somewhat of a one-pitch pitcher.
Spring throws the changeup 31 percent of the time to right-handed hitters, resulting in a .224 wOBA (.243 xwOBA). That's been similar to or better than his outcomes from the most recent seasons against the changeup to righties. However, what does Springs have in his arsenal against left-handed hitters?
Springs uses two different sliders, one being a gyro-like one and the second being a slower pitch that sweeps toward his glove side. Thankfully, the slider (.281 wOBA, .411 xwOBA) and sweeper (.211 wOBA, .178 xwOBA) have been relatively effective against lefties, though the slider looks like it could regress. Springs has been throwing more changeups throughout the season. That aligns with decent changeup results in June (.232 wOBA), though the .365 xwOBA says to be cautious.
Springs' swinging strike rate fell by over two percentage points in 2025 compared to his career average (14 percent) and in 2024 (15.7 percent). With Springs' poor control and his hit rate (29 percent) becoming an issue, his WHIP will rise, leading to a risky deep league starting pitcher.
Quinn Priester, Milwaukee Brewers
38% Rostered in Yahoo Leagues
Priester went from the Pirates' first-round pick in 2019 to being traded to the Red Sox for Nick Yorke in 2024 and then shipped to Milwaukee in April 2025. He was once an enticing First-Year Player Draft (FYPD) pick to another struggling Pirates prospect. Priester's MLB career in 2023 (7.74 ERA, 5.28 xERA) and 2024 (4.71 ERA, 4.19 xERA) has been brutal.
However, Priester has been pretty solid over the past five outings from May 24, allowing a 1.86 ERA, 2.59 FIP, 0.93 WHIP, 15.3 percent strikeout minus walk rate, and a 10.5 percent swinging strike rate. For context, Priester has a 7 percent strikeout minus walk rate and a 9.8 percent swinging strike rate in 2025, so we've seen some slight gains over the past month.
The main change involves Priester throwing more sliders and cutters while lowering the sinker usage over the past month. Priester's sinker typically generates groundballs (63.9 percent), with decent batted ball results against right-handed hitters (.320 wOBA, .334 xwOBA) and lefties (.339 wOBA, .399 xwOBA). He has been throwing his slider to right-handed hitters, around 39-41 percent of the time, with better results in May (.250 wOBA) and June (.000 wOBA).
Meanwhile, Priester has been throwing the cutter more to left-handed hitters, but the results were awful (.407 wOBA, .363 xwOBA). It's worth noting that Priester's cutter is a newer pitch that he's developing after throwing nine in 2024. We've seen the results improve in June via the cutter against left-handed hitters.
That's evident in Priester's cutter allowing a .484 wOBA (.457 xwOBA) in March/April, .467 wOBA (.306 xwOBA) in May, and .148 wOBA (.222 xwOBA) in June. The cutter movement fluctuated within 1-2 inches in the downward and horizontal profile throughout each month. Priester's horizontal release points have changed by five inches in June compared to earlier in the season, a two-inch difference from May.
That indicates Priester's horizontal release point shifted 2-5 inches farther away from his midline, theoretically impacting his pitch movement profiles. The most notable ones involve his pitches losing nearly two inches (1.9) of horizontal movement and over 2.5 inches of downward movement in June.
After examining the cutter locations in May and June, Priester's horizontal release point changes may help him command and locate his pitches. That can be hard to quantify, but one way is to see Priester's Location+ jump to 110 over the past month, higher than his season-long average (98).
The visual below shows the starting pitchers with a five-point increase in their Location+ over the last 30 days compared to the 2025 season, with a minimum of 10 innings. Priester made this list.
Expect the Brewers to help Priester evolve, which we've already seen in 2025. Since Priester lacks above-average control and high-end whiffs, he profiles more like a deep league streamer who generates groundballs.
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