RADIO
Joey Pollizze deep dives 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 20 (2025).
Welcome, RotoBallers, to our weekly Unlikely Aces piece. Every week of the fantasy baseball season, we look at whether emerging pitchers are for real or not. We will then determine if these emerging pitchers are worth a roster spot on your fantasy roster or better left on the waiver wire for one of your league mates to grab.
In this article, we will look at whether Ryne Nelson, Jacob Lopez, and Joey Cantillo are worth grabbing in Week 20 of the fantasy baseball season. These three pitchers continue to put up solid numbers on the mound, and all three of their roster percentages continue to climb this late in the year.
So, should fantasy managers pick up Nelson, Lopez, and Cantillo in fantasy? Are these unlikely aces worth a roster spot in Week 20? Let's dive in and find out.
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Ryne Nelson, Arizona Diamondbacks
What a story Nelson has been for the Diamondbacks this season. The right-hander entered the 2025 campaign in Arizona's bullpen, largely due to his struggles as a starter during both 2023 and 2024. He had a combined 4.76 ERA and 222 strikeouts across 294 2/3 innings pitched in both of those years.
With the Diamondbacks landing Corbin Burnes in the offseason, it made sense to move the young pitcher to the bullpen. In his first few appearances out of the bullpen in 2025, Nelson was very hit-or-miss. He allowed a run in four of his first seven appearances and had a whopping 5.82 ERA to begin the year.
Since then, though, the 27-year-old has been locked down on the mound. He has a 2.88 ERA across his last 19 games (15 starts) dating back to April 29. More importantly, Nelson has been a top-of-the-line rotation arm for this Diamondbacks team since taking over for Burnes, who is out for the season due to an elbow injury.
Nelson has a 2.63 ERA and 57 strikeouts across his past 11 starts. He has allowed two earned runs or fewer in nine of those 11 outings, and the strikeout numbers continue to tick up for the right-hander. The Diamondbacks pitcher has struck out at least six batters in three straight starts, including a season-high eight punchouts in back-to-back outings on July 30 and August 5.
Although Nelson had a clunker in his most recent start against the Texas Rangers in which he allowed five runs across 5 1/3 innings, it's hard to ignore just how dominant he has been on the mound in recent weeks. Just last month, the Oregon product threw three quality starts, which included a six-shutout inning performance with four strikeouts against the Pittsburgh Pirates on July 25.
So, what's been the key behind Nelson's breakout campaign in 2025? The answer is his four-seam fastball.
Nelson is leaning more on his four-seam fastball and less on his off-speed pitches this season. The right-hander is throwing his fastball 63.7% of the time, which is up 8 percent from last year (55.7%). That upped fastball usage has been a large reason for his success on the mound in 2025.
#Dbacks RHP Ryne Nelson's fastball is fantastic. It's 1 of the top 5 most impactful pitches in MLB according to @MLBStats Run Value stat.
Is it too much of a good thing though?
80 of Nelson's 97 pitches last night were 4-seam fastballs. Including the 3-run HR to Wyatt Langford.
— Arizona Diamondbacks | Stats & Info (@DbacksStatsInfo) August 12, 2025
Opposing hitters are batting just .192 against that pitch this season, and 70 of Nelson's 95 strikeouts have come via the four-seam fastball. With a solid slider to go off that four-seam fastball, we are watching a pitcher blossom into a reliable rotation arm right in front of our eyes.
Verdict: There's no doubt that Nelson has pitched well as a starter this season. He has an overall 3.12 ERA across 15 starts, and the strikeout numbers have improved in recent outings. However, the Diamondbacks pitcher is only worth an add in some 12-team leagues right now due to his poor advanced metrics.
His expected ERA (4.07) is 61 points higher than his actual ERA (3.46), and his whiff rate (21.1%), hard-hit rate (44.7%), and expected batting average against (.257) all rank poorly. Given that Nelson only leans on his four-seam fastball, some rougher outings could be on the horizon for him in the next few weeks.
Jacob Lopez, Athletics
We didn't get to see much from Lopez in the majors over the past two years. He only appeared in eight games with the Tampa Bay Rays during the 2023 and 2024 seasons, and most of those appearances came out of the bullpen. The left-hander finished with a 4.76 ERA and 16 strikeouts in those two years.
Then, he was traded to the Athletics in the offseason in the deal that sent Joe Boyle, Jacob Watters, Will Simpson, and the Athletics' 2025 Competitive Balance Round A pick to the Rays in exchange for Lopez and Jeffrey Springs. Although the southpaw started the season down at Triple-A Las Vegas, he has quickly made an impact at the major league level.
Lopez currently owns a 3.30 ERA and 103 strikeouts in his first 19 appearances (15 starts) with the Athletics this season. The thing that has been most impressive about the 27-year-old's season to date has been his incredible strikeout numbers. He has a whopping 10.9 strikeouts per nine innings and has struck out at least eight batters in seven of his last 15 outings.
His best overall performance of the season came last week, when the left-hander tossed 7 2/3 shutout innings with 10 strikeouts against the Washington Nationals on August 7. Everything was working for Lopez in that start, as he used his fastball/slider combination to generate 29 called strikes plus whiffs in the contest.
Jacob Lopez was lights out today against the Nats….
7.2 IP, 3 H, 0 ER, 0 BB, 10 K
18 Whiffs
36% CSW
Season ERA 3.59 with a 1.25 WHIPHe’s a strong play for the rest of the season… even with playing half his games at Sutter Park…
— Nicho Roessler (@NichoRoessler) August 8, 2025
That fastball/changeup combo has been lethal for Lopez throughout the 2025 season. Opposing hitters are batting under .215 on both of those pitches, and 79% of his strikeouts have come on those two pitches. He has also seen some success on his cutter and changeup this year, as both of those pitches have a putaway rate above 17%.
Verdict: After watching Lopez deliver a career performance against the Nationals last week, it quickly became apparent that he should be added in almost all 12-plus team leagues. He continues to pitch well on the mound, and his advanced metrics should give fantasy managers confidence in rostering him the rest of the year.
His expected batting average against (.217), average exit velocity (86.8 mph), strikeout rate (28.2%), and hard-hit rate (32.3%) all rank in the 85th percentile or better. As a result, the southpaw should not be on your waiver wire right now.
Joey Cantillo, Cleveland Guardians
After finishing with a 4.98 ERA across nine games (eight starts) in 2024, the Guardians decided to stick their young left-hander in the bullpen to begin the season. In that reliever role, the results weren't terrible for Cantillo. He had a 3.81 ERA and 36 strikeouts in his first 21 relief appearances through May 26.
However, Cantillo was soon optioned down to Triple-A Columbus after that May 26 relief appearance because Cleveland wanted him to be a starter again. So, the southpaw spent the next five weeks down in the minors building back up before making his first start of the year on July 3 against the Chicago Cubs.
Since then, Cantillo has made every start for the Guardians. The problem, though, is that the 25-year-old hasn't been as consistent on the mound as the team would like. He has allowed at least three earned runs in four of his seven starts and hasn't completed six innings in any of those outings. With a 4.36 ERA during this span, the 25-year-old hasn't emerged as a solid fantasy option just yet.
The good news for Cantillo is that things could be trending in the right direction. He is coming off his best start of the season, in which he threw 5 2/3 innings of one-run ball with three strikeouts against the Chicago White Sox on August 9. In that contest, his changeup worked wonders for him, as he generated six whiffs on that pitch alone.
That changeup has no doubt become a go-to pitch for the left-hander this season. Opposing hitters are batting just .208 against that pitch, and Cantillo's changeup has an impressive 51.2% whiff rate. Given that he throws it the second-most at 32.5%, we should expect the Guardians pitcher to continue to rack up the strikeouts.
#GuardsBall Joey Cantillo’s changeup was deadly, with a 47.8% SwK on Sunday against the Twins. Weirdly, he threw the changeup in the zone 70% of the time.
For context, Cantillo threw his changeup in the zone 45.3% of the time to right-handed hitters in 2025. The Twins hitters… pic.twitter.com/1tdkrL0hhr
— Corbin (@corbin_young21) August 3, 2025
Verdict: Cantillo has shown some encouraging things on the mound this season. He struck out a season-high nine batters against the Minnesota Twins on August 3 and then kept the White Sox's bats at bay in his most recent outings. With an above-average 31.5% whiff rate and a 28% strikeout rate, there are reasons to like the left-hander in fantasy moving forward.
Nevertheless, Cantillo should only be added in 15-plus team leagues right now. His average exit velocity (90.5 mph), walk rate (11.9%), hard-hit rate (47.2%), and chase rate (21.8%) all rank extremely poor, and his 1.402 WHIP is certainly a major concern. Therefore, the 25-year-old isn't necessarily an add in most leagues at this time. He's been way too inconsistent since being moved to the rotation.
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