2 Pirates who cemented their role in 2025, 1 whose future is in question

The 2025 season hasn't been enjoyable for the Pittsburgh Pirates. There aren't very many positives to talk about. But one thing the Pirates have gotten out of it is establishing some players' potential roles for 2026.

Some have gone above and beyond in proving their worth, while others have struggled, leaving question marks about where they stand in the Pirates' plans for the foreseeable future. Who's looking safe, and who's looking questionable?

2 Pirates who cemented their role in 2025, 1 whose future is in question

Spencer Horwitz

Spencer Horwitz had quite the active offseason. He was first traded from the Toronto Blue Jays to the Cleveland Guardians for Andres Gimenez. Then, the Guardians sent him to the Pirates for Luis Ortiz, alongside two more pitching prospects. Before spring training began, Horwitz underwent wrist surgery, putting the start of his season on hold. He didn't perform as expected upon his return either, turning in a .212/.278/.303 line with a .255 wOBA, and 58 wRC+ over his first 72 plate appearances in a Pirates uniform.

However, since then, Horwitz has found his groove. His following 205 trips to the plate have yielded a .279/.351/.410 line, a .335 wOBA, and 114 wRC+. He has an above-average 9.8% walk rate to go with a quality 18.5% strikeout percentage. The only real criticism is that he isn't hitting for much power, with a .131 isolated slugging percentage. But given that he was coming off wrist surgery and is doing everything else well, this is forgivable, and will likely continue to improve as he gets further away from the surgery.

That strong rebound from a slow start to the season has helped Horwitz put up league-average numbers on the year. He has a .315 wOBA, .714 OPS, and 99 wRC+. He's gotten off to a scorching start to August, with 13 hits, including two home runs, just seven strikeouts, and five walks over his first 52 plate appearances.

On top of all of that, Horwitz has been a solid defender at first base for the Pirates. He has +1 defensive runs saved and outs above average in only 565 2/3 innings played at the position. Horwitz has been exactly what the Pirates have needed at first base. He may still need a platoon partner against left-handed pitching, but he is a strong-side platoon bat with quality defense at first base. He's in good standing for 2026.

Isaac Mattson

If you told a Pirates fan in April that one of the most valuable relievers on the team would be Isaac Mattson, they probably wouldn't believe you or would've thought something went horribly wrong with the bullpen. In this case, Mattson has just been really good. He may end up being a closer option next year.

Mattson has pitched 29 1/3 innings this year with a 2.15 ERA, 3.28 FIP, and 1.02 WHIP. His 9.2% walk rate is about average for a relief pitcher, and he has struck out nearly 30% of opponents he has faced. His 20.2% K%-BB% is better than well-established late-inning arms, including Andres Muñoz, Felix Bautista, Matt Strahm, and just below the likes of Devin Williams (21%) and Tanner Scott (21.2%). Mattson has been great at limiting hard contact, too, with an 88.4 MPH exit velocity and 4.2% barrel rate, leading to a 0.92 HR/9.

In terms of win percentage added, Mattson's 0.77 mark is the second best on the Pirates' active roster, only behind Dennis Santana. He is even ahead of David Bednar (before his trade). It's not as if he has been a low-leverage reliever either. He has a 1.36 average leverage index on the year, and a 1.59 mark since the start of July.

Mattson has gone from independent league ball to a quality reliever for a Major League team. He has been a massive surprise for the Pirates this year, and has done everything he could possibly do to set himself up for more high-leverage innings down the road. Mattson should very much be in the mix for save opportunities in 2026.

Joey Bart

Bart was acquired by the Pirates in April 2024 after the San Francisco Giants DFA'd the former second overall pick. He then proceeded to make waves in the Pirates' lineup, turning in a strong .265/.337/.462 line, .347 wOBA, and 121 wRC+ over 282 plate appearances. Bart had an unimpressive 7.8% walk rate and 25.9% strikeout rate, but the biggest positive he brought to the Pirates was a power bat. Bart had 13 home runs and a .198 isolated slugging percentage. 

Bart was expected to play a key role with the Pirates this year and provide middle-of-the-order-type pop. Unfortunately, he has only hit .247/.354/.318 with a .309 wOBA, and 95 wRC+. Bart is walking far more often with a 12.7% walk rate while maintaining a similar 26.9% strikeout rate, but has hit two home runs in 260 plate appearances. His isolated slugging percentage fell all the way down to .072. 

There has been relatively no change in Bart's exit velocity and barrel rate. In 2024, he had an 88.1 MPH exit velocity and 9.4% barrel rate. This year, he has an 88.6 MPH exit velocity and a 9.2% barrel rate. His decreased power output comes from his swing decisions. Bart had a fast swing rate of 51% in 2024, but that has plummeted to just 43.8% this season. If Bart hit for power this year, he would have been one of the most productive catchers with the bat in their hands.

It also doesn't help that Bart's defense is lacking. He has -5 defensive runs saved and -2.9 framing runs. He is in just the sixth percentile of pop time at 2.03 seconds. Baseball Savant pins his fielding run value at -3 (24th percentile). Bart's defense has been so lackluster that the Pirates have potentially toyed with the idea of him at first base, having him take grounders at the position.

Bart is still controlled through 2027, so the Pirates can give him the opportunity to rebound next year. But the Pirates tinkering with him at first base definitely leaves questions about how they view him for 2026. Even with Henry Davis producing much less with the bat this year, the Pirates are now favoring his defense and work with the pitching staff over his hitting.