One available prospect from each Mitch Keller trade suitor Pirates fans should watch

Mitch Keller has pitched himself into being one of the best arms on the trade market this deadline. The right-hander boasts a 3.69 ERA, 1.20 WHIP and 100 strikeouts across 127.0 innings pitched this season. Keller also sits tied for second in baseball with 15 quality starts. He joins Zack Wheeler, Bryan Woo and Logan Webb in that tie for second. The quartet only trails Framber Valdez, who recorded his 16th QS last night.

Of all the potentially available starting pitchers, Keller offers the most team control of the top arms on the market. Comparable players Merrill Kelly and Zac Gallen are both set to hit the open market after the 2025 season. Joe Ryan has two more years of arbitration before his ability to become a free agent after 2027. Keller remains under contract through the conclusion of the 2028 season.

The rival Cubs lead the pack of favorites to land Keller just two days before the trade deadline. Other teams that find themselves in the mix include the Yankees, Red Sox, Blue Jays, Mets, Astros and Giants. If Ben Cherington navigates this situation correctly, he should net at least one high-ranked prospect from the team he chooses, even as shedding Keller's salary (and shrinking the return, most likely) undoubtedly remains a Bob Nutting priority. Look for these names in a potential return.

Prospects Pirates must target in Mitch Keller trade talks

Owen Caissie – Chicago Cubs

Caissie, a 23-year-old Canadian outfielder, ranks as the 36th-best prospect in baseball and tops the Cubs’ system, according to MLB.com. Caissie currently sits in his second full season with Triple-A Iowa. The lefty has shown improvement nearly everywhere from 2024 to 2025. Caissie slashed .278/.375/.472 with 19 home runs, 29 doubles and 75 RBI over 127 games last season.

So far in 2025, he boasts a similar .278/.377/.563 slash line while already eclipsing his previous season’s home run total at 20. Caissie has added 24 doubles and 46 RBI over his 81 games this year. The only major knock on the outfielder comes in his inability to catch up to the fastball at times, along with his high strikeout rate. Caissie went down 164 times in 120 games in Double-A in ’23, 156 times in 127 games in Triple-A in ’24 and 105 times so far this year. At the end of the day, his raw lefty power translates very well to PNC Park.

Rafael Flores – New York Yankees

Signing as an undrafted free agent in July 2022, Flores has become a quick riser over the past two seasons. The catcher/first baseman began the 2024 campaign in High-A Hudson Valley before a midseason promotion to Double-A Somerset, where he played 87 games this season. Flores put up solid numbers, including a .287/.346/.496 slash line, 15 home runs, 23 doubles and 56 RBI in those 87 contests.

That production earned the 24-year-old a promotion to Triple-A this month. The 2024 Yankees Minor League Player of the Year generates above-average power with his 6-foot-4 frame. There remains developing to do behind the dish, but the Pirates have shown their ability to churn out good defensive catchers.

Flores is not ranked in baseball’s Top 100 Prospects and sits seventh in New York's system, but remains a solid potential return piece.

Jhostynxon Garcia – Boston Red Sox

Singed out of Venezuela in July 2019 at just 16 years old, Garcia made his professional debut in the Dominican Summer League in 2021. While the outfielder struggled initially in pro ball, he broke out in 2024 between three minor-league levels. The now 22-year-old has risen from Low-A Salem to Triple-A Worcester and appears to be knocking on the door of the big leagues.

Outside of his 53 games in High-A, Garcia has produced the best raw numbers in his 48 games in Triple-A. That includes a .291/.364/.524 slash line, 11 home runs, seven doubles and 31 RBI. Garcia addresses an immediate need for the Pirates in the corner outfield, with an MLB ETA of mid-2026 at the latest. A late September debut could not be ruled out if the Pirates acquire him as well.

Best of the Rest

The Mets could have to part with their fourth-ranked prospect Carson Benge in order to acquire Keller. The outfielder has enjoyed a breakout 2025 campaign between High-A Brooklyn and Double-A Binghamton. The 22-year-old has a .315/.428/.508 slash line, nine home runs, 22 doubles, five triples, 52 RBI and 18 stolen bases in 81 games thus far.

San Francisco could offer up their fifth-best prospect Bo Davidson. The 23-year-old outfielder was signed as an undrafted free agent in July 2023 and has quickly risen through the team's prospect rankings. Davidson's lowest tool projects as 50-grade power and fielding skills; he also possesses 55-grade hit and arm attributes and 60-grade speed. He was recently promoted to Double-A thanks to his 11 home runs, 57 RBI and .304/.402/.498 slash line across 78 games this year.

Toronto and Houston do not offer the potential return of near-MLB ready bats the other teams do in the hunt for Keller. Toronto could offer eighth-ranked farmhand Yohendrick Pinango. The 23-year-old has spent half the year in Triple-A Buffalo. Houston’s prospect pool remains weak. Third-ranked prospect Walker Janek could potentially headline a deal, but remains down in High-A, too far away for his big-league impact to clarify itself.