The team will make another roster move before the game Friday against Atlanta.
Chacin was 0-3 with a 7.30 ERA this season. He was coming off a performance Tuesday night against the Los Angeles Dodgers in which he gave seven runs and 11 hits in just 4 2/3 innings. The 24-year-old hasn't won since Aug. 28.
Before the game Wednesday, manager Jim Tracy hinted a move could be made with Chacin so he could work on ironing out his mechanics. Said Tracy: "We have to move forward and keep investigating. We need this guy."