Fantasy Baseball League Winners: Unlikely Aces Worth A Roster Spot? (Week 15)

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 15 (2025).

We have seen plenty of unexpected pitchers become strong fantasy options so far this season. No one saw Kansas City Royals starting pitcher Kris Bubic breaking out in his return as a starter, or Matthew Boyd putting together an All-Star campaign. These two unlikely aces quickly emerged as must-rostered players early in the first half.

In this article, we will look at whether Lucas Giolito, Trevor Rogers, Mitch Keller, and Emmet Sheehan are worth grabbing in Week 15 of the fantasy baseball season. All four of these pitchers have thrown the ball well in recent weeks and are much deserving of being added in fantasy leagues.

So, fantasy managers should pick up Giolito, Rogers, Keller, and Sheehan in fantasy leagues? Are these unlikely aces worth a roster spot? Let's dive in and find out.

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Lucas Giolito, Boston Red Sox

There's no doubt that it took Giolito some time to find his groove this season. That makes total sense, considering he missed the entire 2024 season due to an elbow injury. The right-hander had a 6.42 ERA and 27 strikeouts across his first seven starts in 2025. Since then, though, he has been almost untouchable on the mound.

Giolito has allowed just three earned runs across his last 32 2/3 innings (0.83 ERA) dating back to June 10. The 30-year-old has thrown a quality start in five straight starts and threw a season-high 7 2/3 innings with one run allowed against the Washington Nationals his last time out. Not many pitchers have been as dominant as he has been in recent weeks.

Lucas Giolito's past 5 starts 😳:

32.2 IP
0.83 ERA
31 K pic.twitter.com/zGX0ggu7h3

— MLB (@MLB) July 4, 2025

This has been the best stretch of Giolito's career, and it appears that he is fully back from his elbow injury. There isn't a big difference in Giolito's arsenal this season as in years prior, but he is leaning on his fastball more than usual. The Red Sox starter is throwing his four-seam fastball 49.2% of the time, which is his highest since the 2020 season.

That fastball usage has been a large reason for Giolito's recent success. His velocity has been up over his last few outings, and 28 of his 58 strikeouts this season have come on the heater. In his last start against the Nationals on July 4, the 30-year-old's four-seam fastball topped out at 96.3 mph while generating 17 called strikes + whiffs in that contest.

Verdict: There has been a lot to like about Giolito's recent run. He is striking out more batters and seems to be in a groove on the mound, finally. However, some regression is expected to come the right-hander's way in the next few weeks. His expected ERA (4.78) is 112 points higher than his actual ERA (3.66), and his 21.1% whiff rate is not an encouraging sign moving forward.

Therefore, fantasy managers shouldn't expect Giolito to pitch this well for the rest of the season. Still, he should be considered an add in most 12-plus team leagues right now, especially with a start at home against the Colorado Rockies upcoming on Wednesday.

Trevor Rogers, Baltimore Orioles

The Baltimore Orioles made a splash at last year's trade deadline to acquire Rogers from the Miami Marlins. The left-hander was expected to help Baltimore in the postseason, but that never came to fruition due to his struggles. He had a 7.11 ERA in his first four starts in Baltimore and was eventually optioned down to Triple-A in August.

Nonetheless, Rogers has been a completely different pitcher in the majors this season. He tossed 6 1/3 scoreless innings in a spot start against the Boston Red Sox on May 24 before earning a spot on the roster in the middle of June. In his first five starts with the Orioles in 2025, the southpaw has a 1.57 ERA and 24 strikeouts across 28 2/3 innings pitched. 

Orioles pitchers with a bWAR over 1.0:

1. Trevor Rogers — 1.4 WAR

That’s it. That’s the list.

— Jacob Calvin Meyer (@jcalvinmeyer) July 7, 2025

Given how Rogers has looked on the mound this year, most fantasy managers don't know whether to add him or not. After throwing 6 2/3 shutout innings with six strikeouts against the Atlanta Braves his last time out, his rostership in all formats continues to climb. That's not a surprise since opposing hitters haven't been able to find much success against him this year.

The key for Rogers through his first five outings has been his electric fastball and changeup combination. Opposing hitters are batting just .167 against both of those pitches, and 13 of his 24 total strikeouts have come on his heater this season. He is throwing his four-seam fastball 8.7% more than he did in 2024, which has led to him cutting back on both his sinker (17.1%) and slider (11.9%).

Verdict: Fantasy managers shouldn't be ready to say that Rogers is back to his All-Star form. He has only pitched in five games this season, and his 53.2% hard-hit rate is not a great sign for his fantasy value. With that said, the southpaw is not necessarily a must-add in most leagues. We need to see more from him before jumping to conclusions.

For now, though, Rogers should only be streamed in the right matchups. With a start upcoming against the Miami Marlins over the weekend, fantasy managers should consider rolling him out in that great matchup.

Mitch Keller, Pittsburgh Pirates

One of the biggest names in trade rumors right now is Keller. Although the right-hander still has multiple years remaining on his five-year deal, the Pirates could be in the market to trade away one of their most consistent pitchers. The former All-Star currently owns a 3.58 ERA and 89 strikeouts in 113 innings pitched this season.

More importantly, Keller has been on another level on the mound over the past month. Since allowing six earned runs in a start on June 5 against the Houston Astros, the 29-year-old has pitched well for the Pirates. He has a 2.45 ERA and 28 strikeouts in his last six starts, including a dominant seven-shutout-inning performance with seven strikeouts against the Cardinals last week. 

With his 7 punchouts today, Mitch Keller becomes the all-time strikeout leader in PNC Park history! pic.twitter.com/0270nuYxZp

— MLB (@MLB) July 2, 2025

With a six-pitch arsenal, Keller has done a nice job of mixing up his pitches in 2025. He doesn't throw any of his pitches more than 35%, and his sweeper has been a fantastic secondary pitch. Opposing hitters are batting .185 on that sweeper to go with only five extra-base hits and 23 strikeouts.

One of the most noticeable differences in Keller's pitch mix this season is the absence of his cutter. He threw his cutter around 12.3% of the time last year, but that number has dropped significantly to 0.2%. Given that the right-hander struggled to find success with that pitch in 2024, it makes sense that he has thrown just three total cutters this year.

Verdict: With many potential playoff teams reportedly interested in trading for Keller at the deadline, it's becoming increasingly likely that the Pirates could give him away in the next few weeks. That would instantly improve his fantasy value, especially in the wins department. The 29-year-old has just three wins in 2025 despite having a 3.58 ERA.

So, Keller is worth an add in most 12-plus team leagues. He has been pitching well recently, and his overall situation should improve with the trade deadline looming.

Emmet Sheehan, Los Angeles Dodgers

Sheehan has only made two starts in the majors this season. However, he has pitched well in both of those outings. He tossed four innings of one-run ball with six strikeouts against the San Diego Padres on June 18 and delivered five innings of one-run ball with four strikeouts against the Houston Astros on July 6.

Sheehan was working his way back from a UCL injury earlier in the year that ended his 2024 campaign, but he has looked the part in his return. He has a 36.9% chase rate, 27.8% strikeout rate, 2.8% walk rate, 24% hard-hit rate, and a 4% barrel rate in those first two outings with the Dodgers in 2025.

Most of Sheehan's success on the mound in those two starts has come from his off-speed pitches (slider and changeup). The right-hander throws his slider 29% of the time, and that pitch has a 44.4% putaway rate. As for his changeup, he throws it 19% of the time and generates an impressive 46.7% whiff rate on that pitch alone.

Now, if Sheehan wants to continue putting up strong numbers on the mound, he has to limit damage against his four-seam fastball. Opposing hitters are batting .357 with a .500 slugging against that pitch this year, and the Dodgers pitcher only generates an 18.4% whiff rate. Therefore, improvements are definitely needed in that area moving forward.

Verdict: Although Sheehan's fastball has been getting hit hard this season, he is a very intriguing add in some leagues. The 25-year-old was dominant throughout his minor league career, and the potential is there for him to break out in the second half. So, fantasy managers should think about adding him for the next few weeks.

The only problem is that Sheehan might be the odd man out in this Los Angeles rotation once Blake Snell returns. Snell, Tyler Glasnow, Yoshinobu Yamamoto, Clayton Kershaw, Dustin May, and Shohei Ohtani will likely be the team's rotation. Still, the young right-hander is worth an add in the short term.

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