The Mariners announced Wednesday that Iwakuma - who hasn't pitched in the big leagues since last season due to a shoulder injury - has decided to abandon his comeback attempt and leave the organization after seven years, putting an end to his Major League Baseball career.
Per the team, the 37-year-old Iwakuma plans to continue pitching in his native Japan, where he starred for 11 years before jumping across the Pacific in 2012. The Mariners were his only MLB team.
"(MLB is) a very tough league to compete in," Iwakuma said. "Obviously, we all know that I came here to challenge how much I could do here. It worked out very well for me and being able to wear a Mariners uniform for 7 years, that's something special for me."
Iwakuma had re-signed with the Mariners on a minor-league deal over the winter only a few months after undergoing arthroscopic surgery on his right shoulder. While Seattle hoped the pitcher would be able to join the rotation at some point this year, Iwakuma's 2018 season ultimately consisted of two rehab appearances with Class-A Everett last month.
Before injuring his shoulder in 2016, Iwakuma was a mainstay in Seattle's rotation for five seasons, and was named an American League All-Star in 2013. The highlight of his MLB career undoubtedly came on Aug. 12, 2015, when he no-hit the Baltimore Orioles at Safeco Field.
Iwakuma ends his big-league career having compiled a 63-39 record with a 3.42 ERA, 714 strikeouts, and 185 walks over 883 2/3 innings. His 1.14 WHIP ranks as the lowest in Mariners franchise history.