Will Carmen Mlodzinski Work as the Pirates’ Fifth Starter?
Carmen Mlodzinski is shifting from the bullpen to the starting rotation to open the season. How will this transition impact the Pirates in 2025?
When spring training kicked off at Pirate City in Bradenton, Florida, another exciting season appeared to be brewing for the Pittsburgh Pirates. With multiple young starters taking on the rotation, an improving offensive core, and more, fans had high expectations for the club as opposed to last year.
One of the players that fans were arguably most excited for, Jared Jones, looked like he was in a good place to improve throughout this season. Jones showed promising signs despite missing time in his rookie year, and fans were excited to watch him for a full season.
However, disaster struck when the team announced that Jones wouldn’t make his final start of the spring due to elbow discomfort. For fans everywhere, the immediate concern was Jones’ UCL, and many feared that a season-ending injury could be on the horizon.
Thankfully, the team announced that there was no structural damage in Jones’ arm and that he’s dealing with a UCL sprain, but Jones will be shut down from throwing for six weeks as a result.
With this news though, the team shifted its focus to finding a replacement for Jones in the rotation. Despite the numerous impressive outings from Thomas Harrington this spring, the Bucs opted to go with Carmen Mlodzinski to fill this role.
This raised plenty of eyebrows, as Mlodzinski was a former starting pitcher turned flamethrowing reliever. The question remains: Will this move work to their benefit, or will it backfire in a big way?
Mlodzinski’s Transition to the Bullpen
Before we address whether or not Mlodzinski can make the transition back to a role as a starting pitcher, we first need to understand why he abandoned the position in the first place.
In 2020, the Pirates took a chance on Mlodzinski, selecting him with the 31st overall pick in the draft, showing their faith in the right-hander. Mlodzinski was dead-set on starting in professional baseball, and the Pirates showed their willingness to give him this opportunity.
Signing for a sizable bonus of $2.05 million, this selection was one the Pirates viewed very highly. Due to the circumstances surrounding the COVID-19 pandemic, his professional debut was delayed until the 2021 season.
He began his professional journey with the Greensboro Grasshoppers, where he’d pitch very well in a hitter-friendly ballpark. Posting a 3.93 ERA in 14 starts, it seemed like the Pirates had found a hidden gem. Mlodzinski even made it to Triple-A as a placeholder, throwing one game at the level.
Fast forward to the 2022 season though, and he ran into some struggles. Mlodzinski spent the entire season with the Altoona Curve, where he really struggled as a starting pitcher.
To put it simply, Mlodzinski was hit extremely hard. In his first four Double-A starts, he’d pitch to an ERA of 5.28, allowing 11 hits, nine earned runs, and nine walks in 15.1 innings pitched.
He’d follow this up with some more tough stretches, with his worst month coming in July. He’d throw just 11.2 innings across four starts, posting an ERA of 7.71 alongside 15 hits in the same span.
Mlodzinski could not regularly pitch deep into games, making eight starts with under four innings pitched between April and July. In August, he’d throw more innings, but he arguably struggled just as much.
Mlodzinski pitched to an ERA just shy of 6.00 in the month of August, allowing 31 hits in just 25.2 innings pitched. His stat line was far from impressive, especially for a former first-round pick.
He’d finish the season on a higher note, recording a 2.57 ERA in September, but his struggles as a starter made a lasting impression on his reputation as a starting pitcher.
The next season, Mlodzinski fully transitioned to a bullpen role, pitching very well as a reliever during his time with the Indianapolis Indians.
In Triple-A, Mlodzinski pitched to an ERA just barely over 3.00 in just 26.2 innings pitched, recording a strikeout rate of 26.9% in the process. While he had some trouble with his command, walking 10.1% of batters he faced, he still looked far better than he did as a starting pitcher.
He’d eventually even earn a promotion to the big leagues for the first time in his career — a task that seemed more unlikely the year prior.
His Stuff in the Majors
Before the first pitch of the 2025 season, Mlodzinski has been very good in his first 86.2 big league innings. As I previously mentioned, he’d make his MLB Debut during the 2023 season, where he excelled in 36 innings.
In this span, Mlodzinski struck out 22.4% of the batters he faced while pitching to a 2.25 ERA. Not only that, but he’d record a WHIP under 1.30, which was a very impressive mark for someone who’s facing MLB hitters for the first time.
He also flashed an elite ability to not allow barrels — a skill that’s very important amongst any reliever. This may be a result of his 79th percentile fastball velocity, which has been a key part of his success.
Fast forward to 2024, Mlodzinski flashed even more signs of success in some more action than he’d seen the previous season. He threw five more games and 14.2 more innings, and he was very good over that stretch.
Mlodzinski recorded an ERA of 3.38, a 22% strikeout rate, 1.18 WHIP, and an ERA+ of 125. He also flashed far better underlying numbers than the year prior, giving fans plenty of hope for his game moving forward.
For starters, his fastball velocity saw an increase of 0.5 mph alongside an increase in its effectiveness. It generated a hard-hit rate of just 41.7%, an xwOBA of just .288, and a 25.5% whiff rate. This was much better than the fastball he showcased in 2024.
Mlodzinski also saw his slider become a key part of his arsenal, which was something we hadn’t seen the year prior. Generating a whiff rate of over 31%, this pitch was a key part of his ability to get batters out.
In addition to the improvements to his arsenal, Mlodzinski’s ability to limit barrels only improved as well. He limited barrels at an astounding 2.8% clip, which placed him in baseball’s 99th percentile!
He still doesn’t get a large amount of whiffs, strikeouts, or chase, but this may change as his pitches gain even more effectiveness.
Although we still haven’t seen too much out of Mlodzinski at the big league level, what we have seen has been incredibly encouraging. From his stuff improving by the year to his numbers getting better overall, Mlodzinski’s floor appears to be a great seventh or eight inning reliever.
Can He Work as a Starter?
Now that we’ve established his rough transition to a reliever, along with how his stuff has performed against big league arms, this leaves one final question: Will Mlodzinski be able to become a starter once again?
Mlodzinski spent a lot of his 2024 season mainly in a setup role. However, he did pitch in nine games where he threw two innings or more. In these games, Mlodzinski recorded a 2.24 ERA and 17 strikeouts.
While a few two inning appearances are far different from the workload of a full-time starter, his success in these games gives me a decent amount of hope for him as a starter.
Mlodzinski’s success in the rare moments where he had a longer workload isn’t the only thing that gives me hope that he can pull this off, as his statistical improvements also provide optimism. His arsenal has improved every year he’s been on the field, and if this happens again, he’s going to be in a good place.
His lack of whiffs, lower chase rate, and tamed strikeout totals still provide some anxiety. But as his stuff becomes more dominant, these things should improve naturally along the way. However, limiting barrels and hard contact will always remain the key part of his success.
No matter how encouraging his numbers appear on the surface, there will still be a level of randomness in projecting how this move will go. Mlodzinski hasn’t started since 2022, and although he’s been stretched out this spring, returning to the rotation may not be a smooth transition.
This is especially the case when we remember how much he struggled at times as a starting pitcher.
Although it should just be for six weeks or so until Jones returns, Mlodzinski’s success will be a key part of how the Pirates’ 2025 season unfolds.
If this move backfires, the organization still has plenty of arms approaching big league readiness, which will make it easier to pivot. Not only this, but Mlodzinski still possesses an immense amount of potential as a high-leverage reliever, which is still a great outcome for his career.
Written by
Jay Staph, a huge baseball fan and stat nerd, founded and ran his own baseball writing website, BSBWrites, at just 16-years-old. With focal points around prospects,…