PITTSBURGH -- As Spring Training came to a close, Carmen Mlodzinski learned his third season as a pro would look quite different compared to his first two.

Mlodzinski, the Pirates’ No. 24 prospect per MLB Pipeline, transitioned from the rotation to the bullpen this year, marking the first time he’s been used as a reliever in half a decade.

“It’s not an easy task,” Mlodzinski said. “In the past, I’ve worked really hard on making sure I have a good routine -- not necessarily just on start day, but in between start days -- and making sure that routine is really solid. Now, it’s adjusting that routine. Quite honestly, I’m still in the early stages so [I’m] trying to learn what’s going to work and adjust off of that.”

The early returns have been promising for Mlodzinski. Across 13 innings at Triple-A Indianapolis, the right-hander owns a 3.46 ERA and 3.55 FIP, and while his walk numbers are a bit up (4.15 BB/9 in 2023, 3.42 BB/9 in 2022), his strikeout stats are better, too (10.38 K/9 in 2023, 9.48 K/9 in 2022).

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Mlodzinski struggled in his first handful of appearances in 2023, allowing five earned runs across nine innings (5.00 ERA) in his first seven games. But he hasn’t allowed any runs across his past four innings, with six strikeouts and no walks. On May 3, Mlodzinski turned out his most dominant outing since becoming a reliever, retiring the side with two punchouts, while throwing 12 of his 14 pitches for strikes.

“Carmen has competed well here,” said Indianapolis pitching coach Dan Meyer. “[He] just needs to learn the ins and outs of being in the bullpen: You don’t know when you’re throwing. You don’t have as much time to get ready. You can’t get as dialed in in your warm-ups as you’d like to, you might not have enough time. Just that process of learning the bullpen, learning his workload -- daily, weekly and monthly.”

Life in the bullpen is a change of pace for Mlodzinski, who had been a full-time starter since being selected with the 31st overall pick in the 2020 MLB Draft.

In 2021, all of Mlodzinski’s 14 appearances were starts. The 24-year-old had five relief outings last season, but most of those stints out of the bullpen followed an opener. Mlodzinski pitched at least four innings in five of those relief appearances, amassing 20 1/3 innings out of the bullpen. The last time he was consistently used as a reliever was during his freshman season at South Carolina.

“I’m trying to carry on the same mentality I had as a starter,” Mlodzinski said. “For me, that’s being as aggressive as possible, throwing as many strikes as possible. I think there’s certainly adjustments that I’m going to have to make to it. Coming in, it could be just one inning or two innings, understanding what volume you’re going to get that day and what the situation is entitling.”

In addition to transitioning into a new role, Mlodzinski is working on mastering a new pitch: the sweeper.

It has become Mlodzinski’s main secondary pitch, as he is throwing the breaking ball 30.6 percent of the time. Mlodzinski hasn't generated a ton of swing-and-miss with the pitch -- the sweeper has a 30.3 percent whiff rate, while the Major League average whiff percentage for a slider is about 33 percent -- but he has been able to throw the pitch for strikes, posting a called-strike-plus-whiff percentage of 32 percent (the Major League average in 2023 is 30.9 percent).

During Spring Training, Mlodzinski received guidance from Mitch Keller, who incorporated the sweeper into his repertoire last season. Keller, who described Mlodzinski as “a guy who’s capable of spinning a baseball,” showed Mlodzinski how he grips his sweeper, and the two practiced the pitch when they played catch.

“He threw some really good ones,” Keller said. “He was throwing them in a bullpen [session] from what I remember. I know the first ones weren’t as good as he wanted it, but they kept getting better as he kept throwing them and getting more feel for them. I think it can be a big pitch for him.”

Like the sweeper, Mlodzinski’s transition to the bullpen will be a work in progress. Universally lauded for his work ethic, the young pitcher will have to navigate that learning curve in the coming weeks and months.

“Carmen’s a very smart guy,” Meyer said. “He’ll get it. For him, it’s not a rush. Rome wasn’t built in a day. You’re going to have the days where you make mistakes with certain things and we have to learn from them. So, when he does get his opportunity [in the Majors, he will be] as complete as he can be coming out of the bullpen, so that he can help that team win right away.”