Heasley was optioned to Triple-A Omaha on Saturday.
Heasley had been in the majors since early July. In his first seven appearances of his latest big-league stint, he allowed just one earned run in seven innings, but he's given up nine earned runs (including five homers) in 5.1 innings across his last four outings. He'll sort things out in the minors, with Max Castillo taking his place in the bullpen.