Star lefty-righty duo headlines a loaded Mariners farm 

PEORIA, Ariz. -- The Mariners are rolling. They've posted five consecutive winning seasons, the longest streak in franchise history, and made their deepest playoff run ever last October, coming within a game of the World Series. They also have one of the strongest farm systems in baseball and used some of their prospect depth to swing trades for Brendan Donovan and Jose A. Ferrer this offseason.

Seattle's system has many strengths, and perhaps its biggest is the best lefty-righty tandem of pitching prospects in the game. Left-hander Kade Anderson, the No. 3 overall pick in the 2025 Draft out of Louisiana State, and right-hander Ryan Sloan, a second-round steal in 2024 as an Illinois high schooler, both have deep arsenals but may stand out more for their polish relative to their age.

It's not out of the realm of possibility that Anderson, the Mariners' No. 2 prospect and No. 21 overall, could follow the Trey Yesavage path from the first round of the Draft one year to playoff hero the next. Sloan is 18 months younger than Anderson and a year further away from T-Mobile Park, though he could get there next season at age 21.

After topping NCAA Division I with 180 strikeouts in 119 innings and helping LSU to a national title by pitching a 1-0 shutout in the College World Series finals, Anderson has yet to make his pro debut. He has impressed in Spring Training, striking out Cal Raleigh and Julio Rodríguez in live batting-practice sessions and fanning the side (including Xander Bogaerts) against the Padres in his first Cactus League inning.

Anderson shouldn't require much in the way of development. All four of his pitches grade as solid or better and he throws them all for quality strikes. Mariners director of player development Justin Toole said the early focus has been on adding strength to Anderson's 6-foot-2, 179-pound frame to prepare him for the rigors of a full pro season, which has resulted in added velocity on his fastball (sitting at 93-94 mph this spring) and slider (87-88 mph).

"The big thing that has jumped out at us is Kade's compete factor," Toole said. "You see him on the back fields facing Cal and Julio, and he doesn't care. He goes after them and he's calm, composed and confident. We knew he was competitive, but it's even better than anticipated. He's gained some weight, gotten stronger and his stuff has ticked up."

Already 6-foot-5 and 220 pounds despite just turning 20 in January, Sloan (No. 3 prospect, No. 33 overall) drew some comparisons to Gerrit Cole in high school because of his physicality and stuff at the same stage of their careers. Yet the industry's skittishness about using early picks on high school righties allowed Sloan to last until the 55th overall pick in 2024, where Seattle snapped him up with an over-slot $3 million bonus.

Sloan worked 82 innings in his pro debut last season, posting a 3.73 ERA with a 90/15 K/BB ratio between two Class A stops. He showed advanced feel for locating his mid-90s fastball along with the ability to get chases with a mid-80s slider and upper-80s changeup with fade and sink. The Mariners' goals for him this year are to add a couple of pitches and even more polish.

"We had high expectations for Ryan and he has exceeded all of those," Toole said. "His velocity is up and that should help his four-seamer shape. He's added a two-seamer this spring to give him another look and he has a little bit of a cutter, too.

"The biggest thing is challenging him to be the best strike thrower he can, challenge guys in the zone. He can command his slider and offspeed a little better late in counts. It's really not too many things he needs to do besides build on last year."

Camp standout: Colt Emerson (No. 1 prospect, No. 9 overall)

Emerson's bat made him the 22nd overall pick in the 2023 Draft and helped the Ohio high school product reach Triple-A at age 20 last season, when he slashed .285/.383/.458 with 16 homers and 14 steals in 130 games between three stops. World Baseball Classic departures have given him the opportunity for regular playing time in big league camp this spring.

While he hasn't lit up Cactus League pitching, Emerson has impressed the big league staff with his defense at shortstop and third base. There were questions about his long-term ability to stick at shortstop when he was an amateur, but no longer. He has boosted his arm strength, quickness and instincts, further raising the ceiling for one of the best pure hitting prospects in the game.

"The bat-to-ball skills are obvious and the advancements Colt has made at shortstop have been impressive," Toole said. "He's solidifying the improvements to stay at shortstop. His arm has gotten better, his feet have gotten better and now we feel good that he's an everyday shortstop. He's a baseball rat and a gym rat who works his butt off."

Spring Breakout sleepers: Lucas Kelly (No. 29 prospect), Casey Hintz

Beginning with Anderson, the Mariners spent 11 of their 21 selections in the 2025 Draft on college pitchers. Sixth-rounder Kelly (Arizona State) and 16th-rounder Hintz (Arizona) both made brief pro debuts last summer and the two right-handers will take the mound in a March 20 Spring Breakout showdown against the Brewers.

"Casey has a lower arm slot, his fastball has been up to 96 this spring and he has a good slider," Toole said. "Lucas was a two-way guy who hasn't pitched a lot, and he's up to 97 and showing some good shapes. Those are two guys who could come out and show some surprising stuff with different looks in our Spring Breakout game."

Breakout potential: Yorger Bautista (No. 10 prospect)

Nicknamed "La Bestia" ("The Beast"), Bautista signed for $2.1 million out of Venezuela in 2025 and broke into pro ball by slashing .223/.326/.404 with seven homers and 10 steals in 53 games in the Rookie-level Dominican Summer League. The center fielder needs to settle down his approach, but is loaded with tools: well-above-average power, plus speed, right-field arm strength. He'll make his U.S. debut in May in the Rookie-level Arizona Complex League.

"Yorger has unbelievable power from the left side," Toole said. "He carries himself really well. He's a physical kid and the ball jumps off his bat."

Bounceback candidate: Grant Knipp

Though Knipp hit 18 homers in 29 games as a junior catcher/DH at Campbell in 2024, scouts liked him more on the mound after his fastball reached 98 mph during his four relief appearances. Announced as a two-way player when the Mariners drafted him in the sixth round that July, he blew out his elbow last spring before he could make his pro debut and missed all of last year following Tommy John surgery.

Before he got hurt, Knipp homered twice off since-traded 2024 first-rounder Jurrangelo Cijntje in intrasquad games. When he returns to the field in May, Seattle wants to see what he can do on both sides of the ball.

"We're still exploring the two-way avenue," Toole said. "Grant was really good last spring before he got hurt. He's up to 98 with a good slider and we'll see how he develops on the mound. He'll be a reliever and a DH, and if he hits, it will be an interesting conversation."