6 young arms to watch at Mariners camp

February 17th, 2023

This story was excerpted from Daniel Kramer’s Mariners Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

PEORIA, Ariz. -- They no longer have the prospect-heavy identity that made Spring Training the headline stretch on the calendar, but the Mariners nonetheless arrived at camp with a few notable candidates to impact the roster in 2023 -- especially on the mound.

And with George Kirby and Logan Gilbert being eased into action -- and Matt Brash, Matthew Festa and Diego Castillo set to pitch in the World Baseball Classic -- there will be more Cactus League innings to spread.

“We want to take advantage of it,” Seattle president of baseball operations Jerry Dipoto said, “but also understand that for a lot of these guys, [this will] be the first time they go through this in their professional careers.”

Here are six pitching prospects to keep tabs on: 

1. RHP Bryce Miller
No pitcher in Seattle’s pipeline took a bigger step forward last year than Miller, who was twice promoted and finished at Double-A Arkansas while showing a massive uptick in stuff. One American League scout said, “It was like he had a howitzer attached to his arm,” referencing the 100-plus-mph heat that helped Miller achieve a 30 percent strikeout rate. He also has a distinctive mid-80s slider with power and depth that was the better pitch during live batting practice on Wednesday. MLB Pipeline’s No. 98 overall prospect, Miller might project better long-term in relief because of his 6-foot-2 frame and power profile.

2. RHP Prelander Berroa
The Mariners admired the righty’s fastball-slider mix when they acquired him from the Giants in exchange for Donovan Walton last May. But since then, they’ve been even more impressed with his athleticism and acumen, specifically in absorbing analytics on pitch usage, location and count management. The Dominican Republic native has all the makings of a high-leverage late-inning arm.

3. RHP Emerson Hancock
Though Hancock was stalled by right shoulder issues in 2021 and a right lat strain in ‘22, one scout said this is the best he has looked since the club selected him with the No. 6 overall Draft pick in ‘20. The former Georgia Bulldog isn’t sitting 97-98 mph like back then, but he’s been comfortable -- and more importantly, confident -- at 94-96 mph. While he might not possess true plus stuff like Miller, Hancock is a more consistent strike-thrower. And because of his pitch mix and profile, he probably has a more legitimate shot at remaining a starter, even if it’s as a mid- to back-rotation arm. 

4. RHP Bryan Woo
Woo was “the most asked for player” in trade negotiations this offseason, Dipoto said. Adding to that value was that more progressive teams were inquiring, according to a league source. Woo maybe isn’t as mainstream as other recent top prospects like Kirby and Gilbert, perhaps because he didn’t begin his pro career until last June due to his recovery from Tommy John surgery. But despite Woo logging just 57 innings between the Arizona Complex League, Single-A Modesto and High-A Everett, there’s belief that he could accelerate quickly.

5. RHP Taylor Dollard
Dollard has been touted as the most reliable arm in the Mariners' system, and it goes back to the idea that durability is the best ability. He throws strikes, has a good feel for pitching and posts reliable numbers, having made 27 starts over 144 innings last year with Double-A Arkansas. It points to Dollard being among the top reinforcements for the big league rotation, depending on health or other attrition. Dollard is more regarded for his feel for pitching rather than his pure stuff, which features a fastball topping out at 91 mph, an upper-70s slider that misses bats and a slower curve with decent depth. He also has a changeup that rounds out a decent four-pitch mix, another indication that he’ll remain a starter in the long term. But because he lacks heat, a positive transition to the Majors will hinge heavily on his command and location. 

6. RHP Isaiah Campbell
Campbell finally found his footing after moving to the bullpen last June, posting a 1.61 ERA and holding hitters to a .204/.226/.320 (.547 OPS) slash line over 29 relief appearances. Given his huge workloads in college and the season-ending right elbow surgery he underwent in 2021, he might have unearthed his calling card, especially as all his stuff ticked up. Campbell's fastball stood out, reaching 95-96 mph, but his ability to land his slider, which has always been there, really took off. All of it has changed the trajectory of his career. Given that the Mariners recently added him to the 40-man roster to protect him from the Rule 5 Draft and that he’s entering his age-25 season, an MLB debut in ‘23 seems likely.