Seattle Mariners pitching prospect duo MLB's best

Each and every spring training features some buzz around the prospects in camp, and there’s been no shortage of that for the Seattle Mariners this spring.

Top pitching prospects Kade Anderson and Ryan Sloan have been among the players grabbing attention, and both are set to take the hill during the Mariners’ spring breakout game against the Milwaukee Brewers on Friday.

Here’s the Seattle Mariners’ lineup for Spring Breakout game

MLB Pipeline senior writer Jim Callis will be on the call for MLB’s broadcast of the game, and he joined Seattle Sports’ Wyman and Bob on Thursday to discuss some of the Mariners’ prospects.

The conversation started with some high praise for Anderson and Sloan.

“I think the Mariners have the best lefty-righty duo of pitching prospects in all of baseball, and I think they’re both going to get (to the majors) pretty quick,” he said.

The next Trey Yesavage?

After spending most of his first full pro season in the minors last year, Toronto Blue Jays right-hander Trey Yesavage made his big league debut in September and became a key piece of the team’s run to the World Series.

Yesavage, a first-round pick in 2024, posted a 1-0 record and 3.24 ERA with 16 strikeouts over 14 innings in three regular seasons starts in September. In the playoffs, he made six appearances (five starts) with a 3-1 record, 3.58 ERA and 39 strikeouts over 27 2/3 innings. His efforts included earning the win in Game 6 of the American League Championship Series against the Mariners and Game 5 of the World Series against the Dodgers.

Callis could see the 21-year-old Anderson having a similar impact on a Mariners playoff run.

“If you’re looking for somebody to be the Trey Yesavage of 2026 to go from the first round of the draft one year to playoff hero the next, that could be Kade Anderson,” Callis said. “He’s got four pitches: fastball, curveball, slider, changeup. They all can be plus pitches at times. They all can be his best pitch on any given day. And along with the stuff, it’s advanced control and command, it’s a tough competitor.”

Callis believes playing at a high-profile college program like LSU will also help Anderson’s transition to the big leagues.

“He probably, this will sound funny, had more media scrutiny at LSU than he’s going to have in Seattle just because of the way that program is covered,” Callis said. “I just think it’s a mater of getting him pro experience and ready for the longer pro season than anything you really have to be developmentally.”

Shades of Gerrit Cole

Sloan, a 20-year-old right-hander, established himself as one of the premier prospects in the Mariners’ highly thought of farm system during a strong first full pro season in 2025. Sloan was drafted in the second round of the 2024 draft, which Callis views as a steal for the M’s.

“He was as good as any high school right-hander in the 2024 draft, but the way the industry works is people are skittish on taking high school pitchers, especially right-handers, and they’d rather take them with their second pick then with their first pick. He should have been a mid-first-round pick,” Callis said. “He’s got three pitches, he’s got advanced control for a high schooler, he’s very physical.”

Callis sees shades of one of baseball’s pitchers over the past decade in Sloan.

“He kind of looks like – I’m not saying he’s going to be as good – but he kind of looks like Gerrit Cole did at the same stage of Gerrit Cole’s career,” he said. “The Mariners looked up and there’s Ryan Sloan in the second round just sitting there for him, which they didn’t expect, and they jumped on him. He had a really good year last year.”

Hear the full conversation at this link or in the audio player in the top of this story. Listen to Wyman and Bob weekdays from 2-7 p.m. or find the podcast on the Seattle Sports app.

Seattle Mariners pitching prospect duo MLB’s best

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