SCOTTSDALE, Ariz. -- Six months ago, Danny Kirwin was an unsigned, undrafted free agent. A year removed from being Rider University’s athlete of the year, he was back on campus in Lawrence Township, N.J., as a volunteer coach for the baseball program while continuing to revamp his arsenal at Tread Athletics in Pineville, N.C.

The 24-year-old was preparing to spend the 2024 season pitching in the Pioneer League, stretching out as a starter after years of dominating out of the Broncs’ bullpen.

On April 20, Kirwin’s manager with the Oakland Ballers posted a video on social media that showcased the 6-foot-2 right-hander popping 98 mph on the radar gun. Four days later, Kirwin put pen to paper and became a member of the Red Sox organization.

Going from volunteer coach to pro ballplayer came in the blink of an eye. But the dramatic build from Minor Leaguer to Fall Leaguer was more of a slow burn, one that came after a season of consistency with Single-A Salem.

Kirwin pitched with “Boston” emblazoned across his chest for the first time Wednesday night, helping the Solar Sox to a convincing 19-3 win over the Scorpions at Scottsdale Stadium. He struck out five over three frames of one-run ball, pumping 28 of his 39 pitches for strikes.

“It feels outstanding,” Kirwin said. “Ever since I can remember, I dreamed of wearing a big league uniform. So doing this, it's an honor. And I'm excited to be here.”

If there was a league that offered exposure, it seems like Kirwin pitched in it. There was the New York Collegiate League in 2019. The Valley League in 2021. The Coastal Plain League in 2022 and ‘23 -- the latter of which also included the MLB Draft League, where he got his name on a grander stage in front of big league scouts. He racked up 21 strikeouts in 14 2/3 innings for the Mahoning Valley Scrappers, who were managed by former big leaguer Dmitri Young.

The native of Lansdale, Penn., cited his Draft League experience and work with Young as unforgettable key parts of his development. The prominence of the league gave him the stage, but now it’s his stuff that’s drawing acclaim.

Opponents hit just .208 off Kirwin this season in the Single-A Carolina League. Working in a hybrid bulk role that blended the relief work he had become accustomed to with the starting spot he hopes to achieve, he didn't give up an earned run in nine of his 20 outings for Salem. He was particularly hard to square up, limiting batters to a 21.5 percent line-drive percentage and allowing just five homers across 69 1/3 innings while averaging nearly one punchout per frame.

While it was his heater that first thrust him onto the prospect landscape, it was his slider that looked particularly potent during his Fall League debut. He utilized the offering to whiff MLB’s No. 35 prospect Bryce Eldridge (Giants), a 2023 first-rounder who mashed his way through four Minor League levels this season.

“New grip on that actually,” Kirwin said of his slider, “tweaked it about a week before coming here. It's been awesome with the help of the Red Sox to get that pitch where it is now. It feels great and I'm super comfortable with it.”

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Every player arrives in the Fall League from a unique path. On a circuit packed with first-round picks, top prospects and guys knocking on the big league door, there’s often at least one who bucks that trend. With more than 100 players on MLB postseason rosters this season having come through the AFL at some point, it’s an undisputed proving ground, a chance for any player from any background to showcase his mettle.

“It just makes it so much better, to be honest,” Kirwin said of his journey. “And you know, I never lost hope to get signed or to play with a team. It's just an honor.”