Arizona placed Cahill on the DL July 1 after he suffered a hip contusion. Cahill was struck in the area by a line drive two weeks prior, leading to the injury. Around the same time, he also tweaked his pitching shoulder while playing catch.
Cahill, 25, is in the midst of his worst season since his rookie campaign in 2009. In 17 starts this season, he has a 4.66 ERA and 1.407 WHIP. He has 69 strikeouts to 39 walks over 96.2 innings. Cahill's struggles reached a new high just prior to being placed on the DL when he allowed six earned runs in each of his last two starts and had a 9.85 ERA in June.
Over four minor league rehab starts, Cahill allowed 11 earned runs over 22.2 innings.
To make room for Cahill on the active roster, Chaz Roe was optioned to Triple-A Reno. Roe was called up on Aug. 12 and made one appearance before his demotion. He's pitched a total of five Major League games this season and allowed a run in three of them.