PEORIA, Ariz. -- The quote describing Bryce Miller was as succinct as it was descriptive. And the commentary from an American League scout on the Mariners’ top pitching prospect was eye-opening.

“It was like he had a Howitzer attached to his arm,” the scout said, likening Miller’s right extremity to the powerful ranged weapon that falls between cannon and a mortar.

Indeed, Miller saw a big spike in fastball velocity to a 96 mph average last season, while topping out at 100 mph. It was a benchmark he’d chased since being selected in the fourth round of the 2021 Draft -- and it’s why, along with a pair of plus sliders, he could be the next big arm to emerge from Seattle’s pitching-heavy pipeline.

“I’m just excited to come out and throw against big leaguers and see the stuff actually play,” said Miller, who’s in his first big league camp. “I'm ready to go.”

Miller has taken the biggest leap of any pitcher in Seattle’s system since the start of the 2022 season, jumping from No. 24 to No. 5 in the Mariners’ Top 30 prospect rankings by MLB Pipeline. He’ll be No. 2 when the 2023 list is unveiled soon: He (No. 98) and catcher Harry Ford (No. 49) are the Mariners' lone prospects within the MLB Pipeline Top 100.

Miller's rapid climb up the rankings came in unison with his aggressive ascent within the organization. Starting 2022 at High-A Everett and making a brief stop at Single-A Modesto, he finished the year with two months at Double-A Arkansas, compiling a 3.16 ERA with 163 strikeouts and 46 walks and holding hitters to a .195/.273/.303 (.576 OPS) clip. He surrendered just 10 homers and 19 other extra-base hits to the 543 batters he faced. Just as impressive was his durability, as he threw 133 1/3 innings in 27 outings and did not miss a start.

Topping it off, the Mariners say his stuff held up the entire season, notable given that his road to the pros began as a reliever-turned-starter at Texas A&M University.

“I kind of had a weird path to here, and always kind of felt like I had more, that I could do more,” Miller said. “And it's just finally starting to come together and starting to be more recognized. So I wouldn't say it's weird. It's just, for me, it's more like starting to get the spotlight more. I'm starting to put everything together and become more of a pitcher on the mound, and actually, like, pitch instead of just throw.”

Miller was listed at 180 pounds last year, but says he’s up to 202, looking to get to roughly 210 by building muscle in order to prevent fatigue as he eyes another full season. Miller’s innings mark in 2022 was a considerable increase from the previous year, when he threw 56 2/3 innings at A&M followed by 9 1/3 at Single-A after signing with the Mariners. 

“On the prospect lists and stuff, I think going into last season, it was a big question mark as to whether or not I can start and whether I can be durable through a season ... I put on a little bit of weight at last year's strength camp and then last year's offseason and ended up with [133 1/3] innings last year and felt good at the end,” Miller said. “So I don't know if it's a direct correlation as to the weight or just to taking care of my arm more, but that, I'd say, helped.”

Scouting reports mostly suggest that based on his size and pitching profile -- high velocity, gnarly breaking balls -- Miller’s MLB role will be in relief. He added a second slider after watching Matt Brash’s debut in Chicago last April, mirroring the grip he saw on TV. He pairs it with his mid-80s gyro slider to form a combo that stood out during live BP against Cal Raleigh and Tom Murphy on Thursday.

“You're looking at him, is this guy a starter? Is this guy a reliever?” manager Scott Servais said. “And you start projecting out; a lot of it plays into their personality, and how routine-orientated is he? ... I saw a lot of good things [on Thursday].”

Given that the Mariners have six starters, Miller’s clearer path to the Opening Day roster is probably in relief, as one of many in an army of bullpen arms this spring. If he remains a starter, his debut might not be until later.

“It's something I've worked towards my whole life, but I don't really think it's any added pressure,” Miller said. “It's like, that's what I've been working for my whole life, you know? So we're just slowly getting closer to that goal.”