"After collecting all the opinions on his elbow, the best path forward is Tommy John surgery," Montoyo said, according to Hazel Mae of Sportsnet. "He will be leaving us tomorrow."
Giles, 30, was placed on the injured list Sept. 16 with an elbow issue that already cost the closer the majority of the campaign. The surgery and recovery will likely keep him sidelined through 2021.
He's set to become a free agent at the conclusion of the season. In 3 2/3 innings of work in 2020, Giles allowed four runs on four hits, including two homers, and four walks while striking out six.