3 underrated Pirates prospects who could make surprise MLB debuts in 2025

Every Pittsburgh Pirates fan is looking forward to seeing what top prospects like Bubba Chandler, Braxton Ashcraft, and Thomas Harrington can do in the Major Leagues in 2025. They could each play a prominent role on the Pirates’ pitching staff next year, and are each ranked as top 100 prospects in the game.

But the Pirates have plenty more prospects that could make their Major League debuts in 2025 if things break right. Some aren’t nearly as hyped as the aforementioned top 100 prospects, but with their current status, they are on track to get their first taste of Major League action in the very near future.

3 Pirates prospects who could parlay 2025 success into early MLB debuts

Hunter Barco

Hunter Barco was a 2022 draft pick, but the Pirates took the young lefty knowing that they probably wouldn’t get a good look at his capabilities until 2024. Barco underwent Tommy John surgery midway through his final college season. He didn’t return until the second half of 2023, but was put on a limited workload.

Last year, Barco pitched to a 3.27 ERA, 3.29 FIP, and 1.06 WHIP across 66.2 innings. He spent most of his year at High-A Greensboro but made two outings at Double-A Altoona before being shut down. Barco struck out over 30% of batters with a 31.2% K% and a quality 8.3% walk rate. Barco also induced his fair share of ground balls with a 46.7% GB%. This helped the lefty hold opponents to a 0.68 HR/9.

Barco isn’t a flamethrower, but he was clocked up to 96 MPH this past season. His slider looks like an above-average pitch that induced a whiff rate around 42%, according to Baseball America. He also began throwing a mid-80s splitter, which has flashed above-average potential. His second offspeed pitch is a changeup. Barco has shown decent control over his stuff, and his lower arm slot adds some deception to his pitches.

Barco is going into his age-24 season and will open the year at Altoona. That puts him in a good position to potentially make his debut sometime during the second half of the 2025 season. If the Pirates are still in contention by then, Barco could end up being a big boost to the pitching staff down the line.

Sammy Siani

The Pirates originally drafted Sammy Siani as a competitive bonus pick in 2019. Although he always showed some decent speed and fielding prowess, his bat never came along like the Bucs hoped it would - but he’s coming off his best year yet. Siani spent the year at High-A Greensboro and Double-A Altoona, and could factor into the Pirates’ Major League depth chart in the very near future.

Siani opened the year for Greensboro, batting .324/.402/.563 with a .433 wOBA and 170 wRC+. He struck out in just 11% of his plate appearances, with a walk rate of 12.2%. It only took 20 games and 82 plate appearances for the Pirates to promote Siani to Double-A Altoona. He didn’t get off to a great start, as he hit just through his first 219 plate appearances.

On the plus side, he ended the year on a high note. His final 149 plate appearances saw him bat .295/.372/.394 with a .355 wOBA and 124 wRC+. His isolated slugging percentage was still below .100, but he cut his K% down below 20% to 18.1% and upped his walk rate to 10.1%. Siani then went on to put up a strong Arizona Fall League performance, posting a 1.007 OPS in 92 plate appearances.

Siani stole six bases in six attempts in the AZFL, along with 16 during the regular season. He has now swiped at least 15 bags in three straight seasons. Siani saw playing time at all three outfield positions. He has plenty of defensive prowess to stick in center field and racked up a dozen outfield assists in 2023.

If the Pirates need a lefty-hitting outfielder who can play center, then Siani may get his chance in the big leagues in 2025. Although Siani may not have the bat to make a significant impact in the lineup, his speed and defense will give him a chance to carve out a career as a defensive-first, fourth outfield type.

Luckily, after the Pirates left him unprotected ahead of this year's Rule 5 Draft, his Arizona Fall League success didn't sway anyone to claim him. Pittsburgh will receive a second chance here.

Alessandro Ercolani

Alessandro Ercolani hails from the small country of San Marino. After another solid campaign at High-A at just 19, Ercolani may start getting some prospect attention. Baseball America ranked him as a top 25 prospect in the Pirates’ system per their 2025 Prospect Handbook (purchase required). He deserves a top-25 spot after the season he had in 2024. 

Ercolani pitched 76.2 innings at High-A Greensboro, working to a strong 3.29 ERA, 3.50 FIP, and 1.08 WHIP. Batters hit just barely above the Mendoza Line at .202 against him and struck out nearly a third of the time, sporting a collective 29.7% K%. Ercolai was not prone to free passes or home runs, either. He had an 8% BB% and only allowed home runs at an 0.94-per-9 rate.

Believe it or not, these numbers are actually inflated from just one game. In his eighth outing of the season, Ercolani allowed nine earned runs on eight hits, including two home runs, and three walks in just 2.1 frames. With this one game excluded, he sported a 2.54 ERA. His already strong strikeout rate goes up even higher to 31%, while his walk rate drops to just 7.5%, and his HR/9 comes in at 0.73 if this outlier is removed. Ercolani didn't allow more than two earned runs or three hits in any game after this chaotic event.

Ercolani sits around 93-95 MPH with his four-seam fastball. He also throws two breaking pitches. Of the two, his cutter is the better offering, but his slider also projects as a solid weapon. His primary offspeed pitch is a changeup but is considered below average. Ercolani improved his command and control. He walked over 10% of opponents he faced in 2023 at A-Ball Bradenton. Ercolani worked as both a starter and reliever, making nine starts in 24 total games, but he pitched less than two innings just once. Even when he was used out of the pen, he was used in a multi-inning role.

Ercolani is the boldest choice to potentially make his MLB debut in 2025. After all, he will open the season at just 20 years old (turns 21 in late April). The young right-hander will open 2025 at Double-A Altoona. If Ercolani pitches anything like he did outside of his one clunker outing, then it may be possible he gets a late-season promotion.