Fantasy Baseball League Winners: Unlikely Aces Worth A Roster Spot? (Week 13)

Jamie Steed'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 13 (2025).

Welcome back to Unlikely Aces. We're almost at the midway point of the fantasy baseball season, and there's no time like the present to make a big push in our fantasy leagues. 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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Will Warren, New York Yankees

55% Rostered in Yahoo Leagues

Warren was regarded as the Yankees' top pitching prospect heading into the 2024 season. So, it came as little surprise that he made his MLB debut last year. The results were not promising. In six appearances (five starts), Warren had a 0-3 W-L record, 10.32 ERA, 1.90 WHIP, and 29 Ks (22.2 IP).

Following injuries to Gerrit Cole and Luis Gil in spring, the Yankees rotation had some holes to fill in. Despite a so-so spring, Warren started the year in the rotation and has been a mainstay. After 16 starts, Warren has a 4-4 W-L record, 4.66 ERA, 1.33 WHIP, and 96 Ks (75.1 IP).

While Warren's stat line isn't overly impressive, his numbers have improved as the season has progressed. As we can see from the table below, Warren's ERA has been lowering after a rough start. His May numbers were unlucky, and June is trending toward being Warren's best month so far.

One key reason for Warren's improved numbers has been the walks. His 9.5% BB% on the year ranks in the 34th percentile. But Warren has been lowering it throughout the season. After walking four batters against the Red Sox to start June, Warren has only allowed three free passes in his last three starts.

Warren's improvements can also be attributed to his fastball. His four-seamer has a .182 batting average against it. 114 pitchers have thrown at least 300 four-seam fastballs in 2025. Only nine of them have a better batting average against it than Warren.

It should come as no surprise that Warren has thrown his four-seamer more in recent starts. Given that Warren's fastball has been his best pitch, more usage is returning better overall results. The below graph shows Warren's pitch usage for each start throughout the season.

Marcus Stroman is undergoing a rehab assignment and is expected to take the rotation spot of Ryan Yarbrough (who was placed on the IL last weekend). With Luis Gil not expected back until the end of July, Warren has little competition for his place in the rotation.

Warren is 26 years old and doesn't look like he's facing any workload restrictions. He is someone worth adding in all formats. If Warren can continue to build on the recent improved outings, he will end up being one of the best waiver additions of the year.

Jose Soriano, Los Angeles Angels

42% Rostered in Yahoo Leagues

Soriano debuted in the majors as a reliever in 2023. He had a solid rookie campaign, with a 3.64 ERA in 38 appearances (42.0 IP). Last year, Soriano made 20 starts for the Angels (plus two relief appearances) and again impressed. He ended 2024 with a 3.42 ERA (113.0 IP).

Health issues have plagued Soriano throughout his career. He underwent a second Tommy John surgery (TJS) in 2021. Last year, an abdominal infection saw Soriano miss some time. His season ended in mid-August with arm fatigue. So far in 2025, Soriano has remained healthy.

The results have followed his good health. After 16 starts, Soriano has a 5-5 W-L record, 3.39 ERA, 1.42 WHIP, and 80 Ks (93.0 IP). Soriano doesn't offer much strikeout upside. That's largely down to how effective his sinker is, which he throws more than 50% of the time.

Soriano's sinker has 26.0 inches of vertical drop. That is why he has a 66.9% GB% (ground-ball rate), which ranks in the 99th percentile. The graphic below highlights how much movement it has compared to the major league average. This is a guide to how much vertical movement Soriano gets from his sinker.

According to Statcast, Soriano's sinker has the eighth-highest comparable vertical movement (when compared to pitches within 2 mph and 0.5 feet of extension/release) among 278 pitchers. That elite movement will continue to net Soriano the results we've seen so far.

Soriano's 3.46 xFIP and 3.81 SIERA back up his ERA. The only concern (other than health) is Soriano's walk rate. His 10.9% BB% ranks in the 15th percentile and is why he has an elevated WHIP. Even as a reliever, Soriano had a 12.4% BB% and a 9.6% BB% last year, so this is nothing new.

The walks, history of health issues, and low strikeout numbers will hold back Soriano in terms of his fantasy value. Pitching for the Angels won't help it, either. But his ERA is legit, and as long as he's healthy, Soriano is well worth adding in all but shallow leagues.

Landen Roupp, San Francisco Giants

24% Rostered in Yahoo Leagues

An impressive spring landed Roupp a rotation spot in San Francisco. In what became something of a crowded pitching room, the Giants sent Kyle Harrison to Boston in the Rafael Devers trade to ensure Roupp had less competition for his spot. He's pitched well enough to retain it lately.

On the year, Roupp has a 5-5 W-L record, 3.67 ERA, 1.42 WHIP, and 70 Ks from his 15 starts (76.0 IP). In his last seven starts (36.0 IP), Roupp has a 2.50 ERA. Four of those seven starts saw Roupp complete at least six innings without allowing a run.

The downside is that Roupp walked at least two batters in all seven starts. His 9.6% BB% ranks in the 32nd percentile and, like Soriano, is why Roupp has a high WHIP. Also like Soriano, Roupp's most thrown pitch is a sinker. While it doesn't have much vertical break, it does have more tailing movement.

Despite the good movement, Roupp's sinker is less effective than Soriano's. It has a .355 batting average against it. The .311 xBA (expected batting average) against it suggests a bit of bad luck. But no pitcher wants a .311 batting average against their primary pitch.

The good news for Roupp is he's not having to be overreliant on his sinker, which he's thrown 38.5% of the time. Roupp has used his curveball 38.1% of the time and has increased his changeup usage. Roupp's thrown the changeup 15.5% this year, and 23.0% in his four June starts.

In May, Roupp threw his changeup 59 times. He didn't allow a single hit against it. On the year, Roupp's changeup has a .186 batting average against it. Roupp's curveball has been even better (.157 batting average).

The graphic below shows the batting averages against his pitches. It should emphasize how important it is that Roupp continues the recent trend of using his changeup more. Providing the changeup and curveball are featured heavily, Roupp should continue to have good results.

Roupp does offer a little strikeout upside. His 21.0% only ranks in the 42nd percentile. But Roupp has struck out at least five batters in three of his last five starts. Roupp also has seven or more strikeouts in five appearances this year.

Even though he has an identical record as Soriano, Roupp should tally more wins pitching for the Giants. However, he won't be as consistent as Soriano from start to start. That was evident against the Dodgers on June 14, when Roupp failed to get through two innings.

Roupp is still someone I'd add in deeper leagues. If you have lost a starting pitcher or two to injury recently, Roupp would also be one of the first names I'd look for as a temporary replacement in any league. If he can maintain his recent results, Roupp should end up sticking on your roster all year.

Slade Cecconi, Cleveland Guardians

13% Rostered in Yahoo Leagues

Cecconi was the return in the trade that saw the Guardians send Josh Naylor to the Diamondbacks. He didn't make his Cleveland debut until mid-May due to an oblique strain suffered in spring. That was followed by a groin issue, but Cecconi has appeared healthy since debuting.

Cecconi's results have been impressive so far. After seven starts, he's sporting a 3-3 W-L record, 3.38 ERA, 1.29 WHIP, and 37 Ks (37.1 IP). Cecconi had his best start of the season on Sunday, firing seven shutout innings against the Athletics.

He's now got a 2.05 ERA over his last four starts. Although we're only dealing with a small sample, Cecconi has looked more impressive the further removed from the oblique strain he is.

While I would certainly look to add Cecconi to my fantasy teams, there is some expected regression on the horizon. Cecconi has a 3.99 xFIP and 3.87 SIERA. Even if his ERA does regress to nearer those numbers, he'll still be a fantasy asset.

The worry is that Cecconi's ERA regresses further than his xFIP or SIERA suggest. That's due to him being hit hard. As Cecconi's Statcast Profile shows, he's been allowing a lot of hard contact. It'll be tough to sustain a sub-4.00 ERA if that maintains.

As mentioned, we're only looking at a smaller sample than most, given Cecconi's delayed start to the season. As long as he's putting up solid numbers, Cecconi is worth consideration in all leagues. There's no reason why he can't build on his recent impressive starts.

Cecconi is more of a deeper league option, but at least warrants consideration as a short-term replacement or for streaming in shallower leagues. The Guardians have a good record of getting the best out of pitchers. If they do the same with Cecconi, it won't be long before he's a must-add in all leagues.

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