Two of the Seattle Mariners' highest-rated prospects are now one step from the big leagues, and they're taking that step at Cheney Stadium.

The Mariners promoted outfielder Lazaro Montes and infielder/outfielder Michael Arroyo from Double-A Arkansas to Triple-A Tacoma on July 6, the club's official Player Development account confirmed. Both made their Rainiers debuts July 7, according to the Tacoma Rainiers.

Montes, ranked No. 26 overall and No. 3 in the Mariners' system by MLB Pipeline, arrives on a tear: 25 home runs in 79 games at Arkansas this season, leading all Mariners minor leaguers. The 21-year-old Cuban slugger stands 6-foot-5, 250 pounds and posted a .234/.369/.550 slash line. He earned Mariners Minor League Hitter of the Month honors for June after a 12-homer, 1.199 OPS stretch over 25 games.

Montes signed with Seattle for $2.5 million as a 17-year-old out of Havana in 2022 and has been promoted every summer since. He owns back-to-back minor league MVP awards: California League in 2024, Northwest League in 2025. His 101 career home runs across 451 minor league games speak to the 65-grade power scouts have long projected.

The strikeout rate remains a question. Montes fanned at a 30.4 percent clip at Arkansas, though his 15.9 percent walk rate ranked in the Texas League's top 10.

21-year-old is the Mariners' No. 4 prospect and No. 43 overall per MLB Pipeline. The Colombian right-handed hitter slashed .287/.364/.456 with 10 home runs and 13 stolen bases in 65 games at Arkansas. He split time between second base and left field at Double-A, and the Spokesman-Review reported that he is viewed within the organization as a potential Opening Day left fielder in 2027.

His path to the majors this year is narrower. Yahoo Sports' Brady Farkas said he believes Arroyo's likeliest window opens "on Tuesday, September 1, 2026, when the rosters expand, or if somebody gets hurt."

The hitter-friendly Pacific Coast League could amplify both bats. For Montes, it's a chance to prove his power translates against more advanced pitching. For Arroyo, it's an extended audition at a position the Mariners may need to fill next spring.

The promotions mark the Mariners' second major farm-system move of 2026, following Colt Emerson's big-league call-up on May 17. Seattle entered the season with seven Top 100 prospects, per MLB.com's Daniel Kramer, and two of them now call Cheney Stadium home.