This story was excerpted from Alex Stumpf's Pirates Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

One of the recurring themes in the Pirates’ farm system this year has been the emergence of high-end starting pitching. Paul Skenes and Jared Jones have stolen the show in the Majors, and Bubba Chandler and Braxton Ashcraft are Top 100 prospects with Triple-A Indianapolis who have taken a step forward this year, highlighting the Minor League side.

On Friday, Chandler and Ashcraft were joined by another right-hander who has enjoyed a stellar campaign and finally cracked that Top 100 list. Thomas Harrington is now sitting at No. 99 on MLB Pipeline’s Top 100 Prospects list after David Festa of the Twins shed his prospect status, proof that the 23-year-old right-hander’s stock is rising.

Harrington has excelled this season, pitching to a 2.62 ERA over 19 appearances, mostly for Double-A Altoona and Triple-A Indianapolis. He was named the International League Pitcher of the Week after tossing seven scoreless innings on Aug. 17, and his strikeout-to-walk ratio on the year is an impressive 101-to-15.

But when talking about the year he’s had and the success he’s enjoyed recently, what stands out is that this has been a year of self-discovery.

“It’s definitely a year where I’ve taken a step just knowing who I am,” Harrington said. “Knowing how I go about each start, I think that’s a testament about being around professional baseball more and trying to understand what you’re trying to do.”

A lot of that self-discovery centers around his stuff and how he wants to use it. Harrington has six pitches he can go to, offerings that can sweep or dive or change velocities, but they are all centered around a fastball that has emerged as one of the most intriguing pitches in the Pirates’ system, even if it registers in the lower-90s.

The reason why it plays is because Harrington is able to move it around the zone and it gets plenty of movement. He averaged 17 inches of vertical break during his most recent start on Aug. 29, which paired with his arm angle helps the pitch play. It also gives him a solid foundation, because his entire repertoire is centered around playing off of that four-seam fastball.

But when the Pirates drafted Harrington with the 36th overall pick in 2022, he didn’t have a four-seamer. He was a sinkerballer because it felt more natural, but he felt the stuff would play better next to a rising fastball, so he started to make the shift as a pro.

“It was a real challenge for me because I wasn’t used to staying behind the baseball,” Harrington said. “I was just used to getting on the side of it and letting it run. ... The key is having a pretty unique vertical approach angle, combined with my arm slot, combined with a little bit of deception. It kind of jumps on the hitters, even at 92.”

As he experimented to change his seam orientation, Harrington came to the conclusion that the issue was the ball was coming off of his middle finger last. He toyed around with different grips to find one that he felt confident with and that he could pull off the seams at the same time, and he found it by putting a bit more space between his fingers. When it clicked, the whole arsenal got better, including his reworked changeup that he’s going to more often, his sweeper and a cutter that is an evolved version of his old slider.

If you want a taste of how the fastball could play in the Majors, look at Jones. Jones tweaked his fastball grip this offseason to model Harrington after the two talked this winter (and over plenty of rounds of Fortnite), and that extra vertical movement he created has been one of the ingredients to a solid rookie campaign.

That kinship between the Pirates pitchers is something Harrington truly enjoys about this group. The organization has plenty of young starting pitching options, but rather than try to keep to themselves to try to focus on an individual goal, they are all picking up bits of information from one another.

“I think it’s cool that we’re able to help each other out,” Harrington said. “It’s a great group of pitchers here. Being able to lean on each other for information and for help is really cool. I think it’s something that not a lot of organizations have, and it’s really cool that we have it in ours.”