Per the official press release from the Mariners, Iwakuma will report directly to general manager Jerry Dipoto and work with the Mariners' pitchers and pitching instructors at all levels. The 39-year-old officially retired from baseball this past October after spending the last two seasons with the Yomiuri Giants in Japan. He recorded a 63-39 record and 3.42 ERA in 883 2/3 innings with Seattle from 2012-2017.

Iwakuma returned to Japan in 2019, but he has pitched just two innings over the past two seasons due to lingering shoulder issues. The 39-year-old had a great run with the Mariners from 2012-2017, posting a 63-39 record and a 3.42 ERA over 150 appearances (136 starts). He made one All-Star team and finished third in the AL Cy Young Award balloting in 2013.

Iwakuma pitched in the minors in the Seattle organization last season as he worked his way back from September 2017 shoulder surgery. At age 37 next season, he seems unlikely to return to MLB. Iwakuma previously played in Japan for the Kintetsu Buffaloes (now Orix Buffaloes) and Rakuten Eagles.

Iwakuma has been sidelined all season while recovering from a shoulder injury, and this officially rules him out for the remainder of the year. Given his age (37) and recent injury history, this likely signals the end of Iwakuma's major-league career. The veteran right-hander posted a respectable 3.42 ERA, 1.14 WHIP and 63-39 record across parts of six big-league seasons with the Mariners, highlighted by a 2012 All-Star appearance.