Graves, once one of the Reds' most popular players, was jeered after yet another poor performance on May 22 and responded with an obscene hand gesture.
General manager Dan O'Brien found limited interest in a trade for the 31-year-old right-hander, due in part to a contract that guarantees Graves $6.25 million in the final season of his three-year, $17.25 million deal. The contract includes escalators that would increase the salary if he were traded.
Graves had struggled since joining the team's starting rotation two years ago. His fastball has slowed substantially and his control has eluded him. Back in the bullpen, he was 1-1 with 10 saves and a 7.76 ERA as the Reds closer this season.
Graves angered fans by criticizing them for booing after the bullpen blew a six-run lead in the ninth inning on May 2, helping St. Louis rally for a 10-9 win. Graves was booed loudly at Great American Ballpark every time he came in to pitch after that.
On May 22, he gave up five ninth-inning runs in a 9-2 loss to Cleveland and heard catcalls as he left the field. He was in the dugout several minutes later when a fan in seats nearby taunted him. Graves yelled back and made an obscene gesture.
The Reds designated him for assignment the next day, saying the move had more to do with his pitching than his hand gesture.