Diekman became a free agent Thursday after the Athletics declined his team option, Alec Lewis of The Athletic reports.
Diekman was unable to repeat his remarkable 0.42 ERA from 2020 in 2021, but he finished with a perfectly respectable 3.86 ERA, with his 31.7 percent strikeout rate offsetting a 13.0 percent walk rate. The Athletics apparently viewed that level of production as replaceable, but a competent lefty like Diekman shouldn't face too much trouble finding another big-league contract on the open market.