SEATTLE – Seattle Mariners Executive Vice President & General Manager of Baseball Operations Justin Hollander announced today the following roster moves:
- Kade Anderson (#13), LHP, selected from Double-A Arkansas.
- Jhonathan Díaz, LHP, designated for assignment.
The Mariners 40-man roster remains full at 40 players.
Anderson, 22, is set to make his Major League debut and start tonight’s game. In 18 starts with Double-A Arkansas this season, he is 10-1 with a 1.06 ERA (11 ER, 93.1 IP), 13 walks and 135 strikeouts. He has limited opponents to a .147 batting average, a .183 OBP, a .216 slugging percentage and a .400 OPS while posting a 0.64 WHIP.
Anderson is ranked as the No.1 prospect in baseball by The Athletic. He is also ranked as the top pitching prospect and No. 5 overall by MLB Pipeline and the top pitching prospect and No. 6 overall by Baseball America.
The 6-foot-2, 180-pound lefty leads the minor leagues in nearly every pitching statistic, including ERA, SO/BB (10.38), K% (40.5%), Opp. AVG and WHIP. He has held his opponent scoreless in 13 of his 18 starts, allowed 1-run or fewer in 15 of 18 starts and allowed more than 2 runs just once.
He has not allowed a run over his last 20.2 innings dating back to July 24. Anderson has twice tossed 5.0+ innings without allowing a hit this season, on April 10 vs. Wichita and July 24 vs. Tulsa. In his start against Wichita on April 10, he also set a career high with 11 strikeouts. Anderson represented the Mariners in the 2026 All-Star Futures Game at Citizen’s Bank Park in Philadelphia along with his Arkansas Travelers teammate Ryan Sloan.
At 22 years, 47 days, Anderson is the youngest starting pitcher to make their debut for Seattle since Taijuan Walker in 2013 (21 years, 17 days old).
Anderson is the seventh of the Mariners last eight first-round draft picks to make their Major League debut for Seattle, joining RHP Logan Gilbert (2018), RHP George Kirby (2019), RHP Emerson Hancock (2020), C Harry Ford (2021), INF Cole Young (2022) and INF Colt Emerson (2023). In addition, he joins a list of homegrown Mariners players who appear on the Mariners roster, alongside Gilbert, Hancock, Kirby, Young, Emerson, RHP Bryce Miller, RHP Bryan Woo, C Cal Raleigh and OF Julio Rodríguez.
Anderson was drafted by the Mariners in the 1st round (3rd overall) of the 2025 MLB First-Year Player Draft out of Louisiana State University (Baton Rouge, LA). Anderson led the Tigers to the College World Series title in 2025, where he was named the College World Series Most Outstanding Player after allowing 1 earned run over 16.0 innings in Omaha, including throwing a complete game shutout in the CWS final against Coastal Carolina. He was also named 2025 Baseball America College Pitcher of the Year.
Anderson was born in Slidell, Louisiana and attended St. Paul’s School (Covington, LA).
Díaz, 29, was selected from Triple-A Tacoma on August 19 and tossed 1.1 innings of relief in Thursday’s series finale against the Brewers. He has appeared in 24 games for the Tacoma Rainiers this season, making 23 starts and going 7-9 with a 6.22 ERA (77 ER, 111.1 IP) with 83 strikeouts and 42 walks.
The 6-foot lefty has appeared in parts of 5 Major League seasons with the Angels (2021-23) and Mariners (2024-25), going 2-2 with a 4.66 ERA (24 ER, 46.1 IP), 27 walks and 33 strikeouts over 17 career appearances (7 GS). In 6 career appearances with Seattle (1 GS), he owns a 4.09 ERA (5 ER, 11.0 IP) with 9 strikeouts and 3 walks.
A native of Valencia, Venezuela, Díaz was on the roster for Team Venezuela who won the 2026 World Baseball Classic. He was originally signed by the Boston Red Sox as an international free agent and made his Major League debut with the Angels on Sept. 17, 2021.