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Joey looks at three starting pitcher fantasy baseball breakouts, sleepers off to hot starts in 2025. Are Jacob Lopez, Brandon Walter, and Matthew Liberatore for real?
Fantasy baseball managers are continuing to see pitchers break out in the first half of the season. Kansas City Royals starting pitcher Kris Bubic has pitched like an All-Star this year, Atlanta Braves pitcher Spencer Schwellenbach has taken his game to another level in 2025, and Seattle Mariners pitcher Bryan Woo has been lights out on the mound this season.
In this article, we will look at three more potential breakout pitchers: Jacob Lopez, Brandon Walter, and Matthew Liberatore. These three pitchers have pitched well in recent outings and have been strong fantasy options over the past week.
So, are Lopez, Walter, and Liberatore for real? Should fantasy managers pick up these players in Week 13 of the fantasy baseball season? Let's dive in and find out.
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Jacob Lopez, Athletics
2025 Stats: 36 IP, 4.25 ERA, 4.35 FIP, 1.444 WHIP, 49 K
Rostership: 11% in Yahoo! leagues
Lopez spent his first two major league seasons with the Tampa Bay Rays before being an add-on piece in the Jeffrey Springs deal to the Athletics this past offseason. The left-hander wasn't impressive in his limited innings in 2023 and 2024, totaling a 4.76 ERA and 16 strikeouts in eight games (two starts) across 22 2/3 innings pitched.
However, Lopez has shown signs of a breakout campaign in 2025. Although he currently owns a 4.25 ERA, the 27-year-old has pitched much better over the past two weeks. He has allowed just one earned run across his last 16 innings pitched (0.56 ERA) to go with six walks and 23 strikeouts during this three-start span.
Jacob Lopez has been EXCELLENT in his last 3 starts!
16 IP
11 H
1 ER
6 BB
23 KJust 8 career starts but the 27-year-old is showing some promise for the A’s pic.twitter.com/X4A52LFAAF
— Just Baseball (@JustBB_Media) June 20, 2025
Lopez has turned things around in June, especially in the strikeout department. He has struck out at least nine batters in three of his past four starts, which has been key to his recent success. In his last start on June 19, the southpaw threw six innings of one-run ball with nine strikeouts against a solid Houston Astros offense.
While there haven't been any noticeable changes to Lopez's five-pitch arsenal this season, he is generating whiffs at an elite level on both his four-seam fastball and slider. Opposing hitters have an expected .178 batting average on his fastball and a .218 expected slugging on his slider in his first 10 appearances. The Athletics pitcher has a 31% whiff rate on both of those pitches.
Those two pitches have carried Lopez for most of the 2025 campaign, but we shouldn't sleep on his changeup, either. Even though he only throws it about 10% of the time, his changeup has a ton of potential to be a consistent third pitch for him. That was on display in his most recent outing against the Astros, as he generated 11 whiffs on that pitch alone.
Verdict: There's no doubt that Lopez is developing in front of our eyes. He continues to show promise on the mound, and his overall metrics suggest that a breakout season could be in store. The southpaw ranks in the 82nd percentile or better in expected batting average against (.217), whiff rate (30.5%), strikeout rate (29.7%), and hard-hit rate (35.1%).
Therefore, Lopez appears to be trending up. It'll be interesting to see if he will remain a solid fantasy option, especially pitching at a minor league ballpark (Sutter Health Park). Nevertheless, his recent numbers should give fantasy managers some confidence moving forward. That makes him a sneaky add in some 12-team leagues and almost a must-add in 15-plus teams.
Brandon Walter, Houston Astros
2025 Stats: 23 2/3 IP, 3.80 ERA, 3.67 FIP, 1.099 WHIP, 25 K
Rostership: 17% in Yahoo! leagues
With the Astros dealing with some injuries to their rotation in the middle of May, the team decided to call up Walter on May 20 to make his season debut. In that start, he threw five shutout innings with five strikeouts against the Tampa Bay Rays. The left-hander then followed that up by giving up just three earned runs across 12 2/3 innings in his next two outings on May 8 and May 15.
Walter showed a lot of great things in those first three starts. He walked just one batter across 17 2/3 innings, and his best start came back on May 15, when he threw 6 2/3 innings of one-run ball with a career-high nine strikeouts against the Minnesota Twins. It's nice to see the left-hander put together some quality outings, especially since he was designated for assignment by the Red Sox less than 12 months ago.
Brandon Walter with a great start today:
6.2 IP | 6 H | 1 R | 1 ER | 0 BB | 9 K
He has a 1.53 ERA through three starts this season! #Astros #BuiltForThis pic.twitter.com/ZvX3zhAa7F
— Astros Future (@AstrosFuture) June 15, 2025
However, Walter is not a complete pitcher just yet. That was evident in his most recent outing on Saturday, as he allowed seven runs on nine hits across six innings against the Los Angeles Angels. There was a lot that went wrong for the left-hander in that start, but it's a positive sign that he still battled through six innings and generated 14 whiffs on a day where he didn't have his best stuff.
It's easy to see why Walter has had some success in the early going. He leans on his five-pitch mix, and that has kept hitters off balance at the plate. Although he throws his cutter the most at 30%, it's his off-speed pitches (sweeper and changeup) that have done the most damage this year. Both of those pitches continue to be a major weapon for him.
The 28-year-old has a 29.3% whiff rate with a .238 batting average against on his sweeper and a 32.4% whiff rate with a .176 batting average against on his changeup this season. If Walter can trust his changeup more as a putaway pitch, then we could see more consistent outings from him moving forward. His changeup has just an 8.0% putaway rate through his first four starts.
Verdict: There's a lot to like about Walter in a small sample size. His chase rate (35.4%), strikeout rate (25.3%), walk rate (2.0%), and barrel rate (7.1%) all rank in the top half of the league, and the southpaw has pitched well in three of his four starts. With a unique five-pitch mix, the Astros pitcher has the chance to break out this season.
As a result, Walter should be added in some 12-team leagues in Week 13. We shouldn't call him a must-add just yet until we see what he does against a very good Cubs offense in his next start on Friday. He has pitched against four middle-of-the-pack offenses (Rays, Guardians, Twins, and Angels), and his next outing will tell us if he is for real or not.
Matthew Liberatore, St. Louis Cardinals
2025 Stats: 86 1/3 IP, 3.96 ERA, 2.97 FIP, 1.147 WHIP, 71 K
Rostership: 37% in Yahoo! leagues
There have been some ups and downs for Liberatore this season. He started the year with a 2.73 ERA and 51 strikeouts in his first 10 starts before struggling a bit toward the end of May and the beginning of June. In three starts from May 30 to June 11, Liberatore had a 10.29 ERA and just 11 strikeouts across 14 innings pitched.
Nonetheless, it appears that the left-hander is officially back after tossing back-to-back quality starts. He threw six innings of two-run ball with four strikeouts against the White Sox on June 17 and followed that up by throwing seven innings of two-run ball with five strikeouts against the Cubs on June 23.
Having already surrendered his first run and having loaded the bases, LHP Matthew Liberatore got long-time #STLCards killer Ian Happ to hit into a 5-4-3, inning-ending double play.
It might prove to be the most important pitch of the night. It keeps the Cards ahead 2-1. pic.twitter.com/WGAmh7RZuS
— John Denton (@JohnDenton555) June 24, 2025
There isn't a clear reason why Liberatore struggled in those three starts other than missing his spots. He has been relying on all six of his pitches on the mound in 2025 and just shoved against the second-best offense in baseball his last time out. So, fantasy managers are certainly seeing signs of a breakout campaign.
The biggest difference for Liberatore this season is the increased usage of his curveball and changeup. After throwing his curveball just 6.5% of the time and his changeup just 4.6% of the time in 2024, the southpaw now throws both of those pitches more than 12.5% of the time. That increased off-speed usage has led to a ton of success.
Liberatore throws his changeup exclusively to right-handed batters, and those hitters have a .111 batting average against that pitch this year. As for his curveball, hitters haven't been able to do much damage against it. The 25-year-old has a 35.8% whiff rate and a .174 expected batting average against on his curveball this year.
Verdict: Even though Liberatore has posted solid numbers on the mound, his metrics suggest that we should see more inconsistencies from him moving forward. The left-hander's expected batting average against (.265), average exit velocity (91.4 mph), strikeout rate (19.9%), and barrel rate (9.6%) all rank in the bottom half of the league.
That means Liberatore might be a year away from fully breaking out. Still, he should be added in most 12-plus team leagues right now. His expected ERA (3.69) is 27 points lower than his actual ERA (3.96), and his 1.15 WHIP is a nice sign for his fantasy value. He has shown enough this year to make him worth adding, especially since his 33.7% chase rate ranks in the 92nd percentile.
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