PEORIA, Ariz. — Jerry Dipoto stood behind the backstop fence on the back fields of the Mariners’ spring training complex watching the batting practice session with a mixture of intensity and delight.

On the mound was Prelander Berroa, all of 22 years old, facing his teammates in his first competitive situation of his first major league spring training.

With each fastball in the upper 90s that Berroa rifled to catcher Jacob Nottingham, for every mid-80s slider that he snapped off with a nasty downward break and even with the revamped changeup that Berroa brought to spring training, Dipoto reacted in pure delight.

The president of baseball operations side of Dipoto saw a young power arm that could help the Mariners at some point in the 2023 season either as a starter but most likely as a reliever. The pitching nerd side of him saw elite velocity, plus spin rates, nasty movement and potential.

“Oh man,” Dipoto said after Berroa elevated a 99-mph fastball that Colin Moran tried to check his swing on. “That’s so good.”

The Seattle Mariners conducted Spring Training workouts Sunday, Feb 19, 2023 at the Peoria Sports Complex, in Peoria, AZ. (Dean Rutz / The Seattle Times)

Fast-forward to Friday’s Cactus League opener at Peoria Stadium.

Berroa entered the game in the third inning after starter Robbie Ray pitched two scoreless frames.


Scheduled to pitch two innings in his spring training debut, he would face the No. 9 hitter Jose Azocar and the top of the Padres’ stacked batting order that included Xander Bogaerts, Manny Machado, Juan Soto and Nelson Cruz in order.

No soft landings, kid.

But for a kid born and raised in Santo Domingo in the Dominican Republic, facing Soto and Cruz — All-Star players from his native country — was more of a dream than a nightmare.

“I was a little nervous going up there because obviously these are guys that I grew up watching,” Berroa said through interpreter Freddy Llanos. “But I kind of told myself that I do have to kind of keep my composure, get out there and do my job.”

After striking out Azocar, using mostly sliders, Berroa struck out Bogaerts on four pitches, having him waving at a 1-2 slider.

Berroa gave up a single to Machado on a 2-2 slider that stayed up in the zone and walked the always dangerous Soto on five pitches. Facing the 42-year-old Cruz with runners on first and second, Berroa fell behind 1-0 and went to his slider — his best pitch. He threw three of them in a row to strike out Cruz, including an ugly swing and miss for the third strike.

“Very few guys can make Nelson Cruz and Manny Machado and Xander Bogaerts look really bad on one pitch and that’s what Prelander did with his slider,” Mariners catcher Tom Murphy said. “For him to be able to throw it for strikes in the zone, get ahead with it, use it as an out pitch, that was impressive.”


What makes Berroa’s slider so difficult to hit is the break and downward angle. It’s not typical.

“The spin would tell you that it’s going to have more lateral movement than it does,” Murphy said. “With that type of spin and it’s just going straight down, it’s kind of a deceptive little pitch for hitters to get used to.”

That slider is an adjustment made by changing the grip at the urging of coaches back in the Dominican Republic and later Mariners coaches. He had previously held it across the small seams of the ball. Now Berroa holds it on more on the horseshoe part of the seams, similar to Matt Brash and other Mariners pitchers.

“It’s been very successful for me, because I feel like it’s one of the pitches that I can control the most from any of my repertoire,” he said. “It’s one that I can hit strikes zone if I wanted to and out of the strike zone if I want.”

Berroa worked a 1-2-3 third inning, getting three fly-ball outs.

Manager Scott Servais wanted to see how Berroa would handle pitching against the top of the Padres order.


“He knows who’s in the box,” Servais said. “He’s followed those guys as a young player like that. I thought he handled it great. He’s got really good stuff. He has a history of being able to command that breaking ball. We saw it today. It’s a really good slider and he throws it for strikes.”

Not familiar with Berroa? Well that’s because he wasn’t part of the Mariners organization until May 11 of last season. In a trade that didn’t seem consequential at the time, the Mariners sent utility infielder Donovan Walton to the Giants in exchange for Berroa. With Tommy La Stella injured and other players struggling, San Francisco needed help on their MLB roster. Walton was blocked by Dylan Moore and Sam Haggerty in terms of playing time with the Mariners.

Berroa was pitching in the High-A Northwest League at the time. He made the transition from Eugene to Everett. In 13 starts with the AquaSox, he posted a 2-2 record with a 2.41 ERA. In 52 1/3 innings, he struck out a whopping 81 batters with 32 walks.

The Mariners promoted him to Double-A Arkansas, where he finished out the season. He made nine starts, going 2-1 with a 4.37 ERA. In 35 innings, he struck out 53 batters with 25 walks.

While most scouts and analysts, including some with the Mariners organization, believe that Berroa will ultimately be converted to a reliever at the MLB level, the Mariners will continue to work him as a starter, likely in Arkansas. Dipoto has said on multiple occasions that Berroa’s stuff could allow him debut in the big leagues at some point this season.

“Prelander Berroa for Donnie Walton might have been the worst trade of 2022,” an opposing American League scout said. “And it might not be close.”