The Mariners knew Giles wouldn't pitch in 2021 when they signed him to a $7 million, two-year contract. But he appeared in only five games this season, and had been on the injured list since July 9 because of right shoulder tightness.
With his rehab time almost up, and their bullpen in good shape, the Mariners really had no room on their active roster for the 31-year-old Giles, who had been among the AL's top relievers before getting hurt.
"It's a serious injury he was trying to come back from. It was a little bit of a gamble on our side that we could get him back, and you never know how bullpens are going to work out,'' Seattle manager Scott Servais said.
Servais said the Mariners have gotten bullpen contributions from a number of players they weren't counting on ahead of this season.
"A lot of guys have stepped up and done a great job,'' Servais said. "Opportunity-wise, maybe not there, the opportunity that Ken was looking for. ... He wants to pitch in the big leagues, and we just don't have that opportunity for him.''
Giles made his Mariners debut on June 21, and he had six strikeouts and four walks while throwing 4 1/3 scoreless innings in five appearances. He began this season on the injured list with a right middle finger sprain that he suffered in spring training.
Giles' deal with the Mariners included a $500,000 signing bonus and salaries of $1 million last year and $5 million this season. Seattle had a $9.5 million option for 2023 with a $500,000 buyout.
He had Tommy John surgery in September 2020, after pitching in only four games that season for Toronto. He had 23 saves and a 1.87 ERA in 53 games for the Blue Jays in 2019, when he had 83 strikeouts and only 17 walks over 53 innings.
While pitching for Houston in 2017, when the Astros were World Series champions, Giles had 34 saves and a 2.70 ERA in 63 appearances.
In 362 career appearances over eight big league seasons with Philadelphia, Houston, Toronto and Seattle, Giles is 14-18 with 115 saves and a 2.71 ERA. He has 484 strikeouts and 114 walks in 355 1/3 innings.
The Mariners on Thursday reinstated All-Star center fielder Julio Rodríguez and catcher Curt Casali from the injured list while optioning outfielder Jarred Kelenic to Triple-A Tacoma and designating for assignment catcher Luis Torrens.