OAKLAND, Calif. -- Left-handed pitcher Andrew Chafin declined his portion of a mutual option to stay with the Oakland Athletics on Thursday, instead accepting a $500,000 buyout and becoming a free agent.

The A's had decided to exercise the $5.25 million contract for 2022.

Also Thursday, Oakland declined its $4 million contract option for lefty Jake Diekman and he also becomes a free agent. Diekman will receive a $750,000 buyout.

The A's, who missed the playoffs after making the postseason in three straight years, acquired Chafin from the Cubs before the trade deadline. He went 2-2 with a 1.53 ERA and five saves over 28 relief appearances for Oakland.

Fellow reliever Diekman went 3-3 with a 3.86 ERA and a career-best seven saves in 67 outings.