Bummer opted out of his minor-league contract with the Cubs on Friday, Jon Heyman of the New York Post reports.
After being released by Atlanta in May following a 7.63 ERA in 19 appearances, Bummer allowed four runs with a 3:2 K:BB over four innings with Triple-A Iowa. The southpaw has the ability to negotiate with other teams, though it's possible he already has a deal in place somewhere.