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SAN FRANCISCO -- Just because a player isn’t on a Top 30 Prospects list doesn’t mean they aren’t on the Major League radar. And just because a prospect is repeating a level doesn’t mean they haven’t grown as a pitcher.

In both instances, take a look at right-hander Sean Sullivan. The 23-year-old right-hander isn’t on MLB Pipeline’s Top 30 Prospects list for the Pirates, but he has been one of the bright spots for Double-A Altoona early this season, recording a 3.06 ERA with 2.2 strikeout-to-walk ratio over his first four starts.

Sullivan had a decent showing with Altoona a year ago, posting a 3.88 ERA over 113 2/3 innings, which was enough for the Pirates to invite him to Major League Spring Training this year. He didn’t have any real chance of making the team. It was more of a learning experience to give him a taste of what that next level could look like. However, with some late free-agent signings and the decision that Paul Skenes should take longer to build up for the season and therefore start in the Minors, there really wasn’t a spot for Sullivan to advance quite yet. As a result, the 2021 eighth-round Draft pick out of the University of California found himself back with the Curve.

That’s not necessarily a bad thing for Sullivan, who has been taking this past year and the offseason as a learning experience.

“I think it’s where you become a pitcher,” Sullivan said. “That’s where you find your strengths and how they play and how they work best. I spent a lot of last year figuring all that out.”

For Sullivan, a lot of that jump from being a thrower to a pitcher has to do with sequencing and, perhaps more importantly, approach. A lot of it centers around building on his strengths and attacking hitters with that stuff. Earlier in his career, the temptation was to try to pitch to a hitter’s weakness. Now, the goal is to pitch to his strength. If that happens to also be a hitter’s strength, OK then. Try to hit it.

It helps that Sullivan feels like he has a better understanding of what his strengths are now. His fastball sits in the low 90s, so he needs to rely on movement and command more. Last year, he interpreted that as needing to get horizontal movement. Sullivan had a lower arm slot, which created a bit of run on his pitches. His primary breaking ball toed the line between a slider and a cutter, which also spun outward. He leaned into that natural cut, trying to get hitters to chase out of the zone with left-to-right movement.

Reassessing his repertoire this offseason, Sullivan worked to improve overall. Working with Minor League pattern and throwing coordinator Vic Black in Bradenton, Fla., the focus centered around what type of movement he should be trying to get. His changeup is his “bread and butter” pitch, and it has downward bite. Building off of that strength, Sullivan reintroduced his curveball, raised his arm slot and leaned into more vertical movement. Instead of being an east-west pitcher, he was going to be north-south. He was going to focus on changing eye levels and try to make everything look like a fastball out of the hand.

“It’s easier to see [my stuff] in and out [of the strike zone],” Sullivan said. “It’s tougher for them to see up and down. … I found that, even though I had success last year, this is the direction I needed to be headed in.”

So far, it has yielded encouraging results for Sullivan. That’s good, because this is a pivotal season for him. A midseason call to Triple-A Indianapolis seems very possible. If that happens, his next call to Major League Spring Training could potentially be a lot more than just getting a taste of what big league camp is like.

“I feel like I’m on a pretty good path,” Sullivan said. “I’ve just got to keep going. Keep my foot on the gas.”