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Frank's deep dive into starting pitcher fantasy baseball breakouts, waiver wire adds for Week 13 of 2026. Are these unlikely aces potential league winners?
It's time for the 12th edition of our Unlikely Aces article for the 2026 MLB season. This is a page where we focus on pitchers who are performing above expectations, known as "Unlikely Aces." The goal here is to take a closer look at their profiles to see if what they're doing is sustainable.
This season, it's been especially tough for pitching, as there have been numerous injuries, most notably to Garrett Crochet and Cole Ragans, who have been out for a while. Ragans is likely done for the season. That's why it's especially important for Unlikely Aces, as they're able to keep your starting rotation afloat while you manage with injuries. The big question to consider here is, can they keep it up?
This week, we're focusing on Will Warren, Foster Griffin, and Andre Pallante. A couple of these pitchers have been performing well lately, while another has some untapped potential. As with every one of these articles, roster percentages referenced here are from Yahoo! leagues. For the second week in a row, I've chosen more highly rostered players, so the focus is not on whether to pick them up but on whether you should trade for them.
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Will Warren, New York Yankees
80% Rostered
Warren has put up a 3.45 ERA and a 1.33 WHIP with a 24.7% strikeout rate and a 7.6% walk rate in 78.1 innings. You have to like how he's trimmed his walk rate from 9.1% to 7.6%. But what's even more impressive is how Warren has been able to limit hard contact much more frequently this season. His hard-hit rate has fallen from 45.2% to 35.5%, while his barrel rate has also decreased, going from 10.8% to 5.7%.
When looking at Warren's underwhelming metrics, we see a 17.1 K-BB%, up from 14.9 K-BB%. He also has a career-high 3.72 SIERA, an improvement from last year's 4.08 SIERA. One thing Warren has been able to do this year is get hitters to chase more often, as his O-Swing% has increased from 24.5% to 29.4%.
Will Warren, Frisbee 83mph Sweeper. 🥏
19 inches of Horizontal Break pic.twitter.com/8BcoDFY1oa
— Rob Friedman (@PitchingNinja) May 2, 2026
The Yankees' right-hander gave up six runs (two earned) against the Reds in his last start, but he was able to rack up eight strikeouts, which is his most since May 1st. It's encouraging to see Warren get strikeouts at a high rate once again, as his previous five outings maxed out at five.
When you look at Warren's arsenal, you can see that there's upside for more. His four-seamer has been excellent this season, inducing an impressive .270 xwOBA, as hitters are struggling to generate hard contact off the pitch. His sinker has been a reliable pitch that can get outs for him, allowing a .324 xwOBA. Warren just needs better results from his sweeper, which is giving up a .367 xwOBA.
One of the main selling points with Warren is that he pitches for the Yankees, who have been one of the best teams in baseball this season. When you look at their rotation, you see a deep group that the organization has been able to develop effectively.
I'm optimistic that they can continue to do so with Warren. Simply put, this is a team that knows what they're doing. Warren is still only 27 years old, so I can see him continuing to get better as the season progresses.
Verdict: Warren is an underrated arm that has upside for even better results than he has so far.
Foster Griffin, Washington Nationals
67% Rostered
Foster Griffin has been an excellent signing for the Nationals so far. After putting up a 1.62 ERA in 78 innings in Japan last year, the Nationals brought him in on a one-year deal worth $5.5 million. Currently, Griffin has a 3.15 ERA and a 1.06 WHIP with a 23.8% strikeout rate and a 6.1% walk rate. You have to love the 17.6 K-BB%, which is rock-solid.
While Griffin has had issues with the long ball, as highlighted by a 1.58 HR/9, the underlying metrics look good, including a 3.64 SIERA. Even though Griffin isn't going to have numbers that pop off the page, he's still a dependable innings-eater to round out your rotation. We also have to remember that his current ratios are inflated by his May 14th outing, where he gave up nine earned runs.
Griffin has a robust arsenal, including a cutter (30.5% usage, .322 xwOBA), four-seamer (17.8% usage, .350 xwOBA), sweeper (14.9% usage, .313 xwOBA), sinker (11.0% usage, .326 xwOBA), curveball (10.4% usage, .337 xwOBA), changeup (9.8% usage, .253 xwOBA), and splitter (5.6% usage, .235 xwOBA).
The 30-year-old lefty essentially throws the kitchen sink at opposing hitters. Seven pitches are pretty much unheard of in today's game.
Having so many pitches to choose from can raise Griffin's floor. When he doesn't have a feel for one of the pitches, he can just lean into another one. While he's got to do a better job of limiting hard contact (11.0% barrel rate allowed), you have to be happy with the returns he's given you so far.
On pitch No. 99, Foster Griffin ties a career high with 9 strikeouts! pic.twitter.com/cyAaLNM1hb
— MLB (@MLB) June 23, 2026
We just saw Griffin have a great outing against a tough Phillies offense, where he went 7.1 innings, allowing four hits and one earned run with zero walks and nine strikeouts. Griffin has found a nice rhythm lately, as he's given up one earned run in each of his last four starts. Keep riding the wave with him.
Verdict: While it wouldn't surprise me to see another blowup outing at some point, given the high barrel rate, Griffin is a dependable arm for the backend of your rotation.
Andre Pallante, St. Louis Cardinals
46% Rostered
Andre Pallante has been a dependable innings-eater for the Cardinals, putting up a 3.59 ERA and a 1.19 WHIP with an 18.5% strikeout rate and a 7.2% walk rate in 82.2 innings. While the strikeout rate remains well below average, at least it's up three percent from last season. Pallante's walk rate is also down 1.5%, which is encouraging.
The underlying metrics indicate that some regression is coming, as highlighted by a 4.14 SIERA, but at least it's not that much higher than his ERA. This is a sinker-baller who is in a nice rhythm right now. He's putting up a 54.0% groundball rate, which has helped him rack up quality starts lately.
Pallante has given up two earned runs or fewer in four consecutive outings. During this stretch, he's gone at least six innings in three of those starts, including seven against the Padres on June 16th. Simply put, he's on a roll right now, so you have to ride the wave when he has a feel for his arsenal.
Andre Pallante secures his ninth win of the season, throwing six strong frames for a 3-2 series opening win vs. Diamondbacks. #stlcards manager Oli Marmol shares his thoughts on how Pallante has grown into his role as a starter: "This is a reminder for all of us of the… pic.twitter.com/6w2uXho4et
— Tamar Sher (@tamar_sher) June 23, 2026
The Cardinals' righty is doing a great job limiting hard contact, including a 35.1% hard-hit rate, which ranks in the 73rd percentile. The key to Pallante's success so far has been his slider, which he uses 29.9% of the time. It's his best pitch for strikeouts, inducing a 32.0% whiff rate. The knuckle curve has also been effective, allowing a .263 xwOBA.
Pallante is never going to be a pitcher you get excited about, but he can be reliable while in a rhythm, as he is now.
Verdict: Hold Pallante while he's in a groove, as he is now.
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