Garza, 29, was scheduled to pitch for the team's Double-A affiliate. It would have been his first rehab start after a lat strain caused him to miss spring training and the start of the season. Hoyer downplayed the injury and said the team was just being cautious.
Garza went 5-7 with a 3.91 ERA last season while missing time with a stress fracture in his elbow. He went 10-10 with a 3.32 ERA in 2011, his first year with Chicago, and he owns a 57-61 record with a 3.84 ERA in parts of seven big-league seasons. Garza is scheduled to become a free agent this offseason.
Despite owning one of the worst records in baseball, the Cubs actually boast a very strong starting rotation. Their starting staff's 3.11 ERA heading into Tuesday's action was the fourth best in baseball, behind only the Cardinals (2.55), Red Sox (2.62) and Braves (2.91).