His stint on the DL with discomfort in his lower back is retroactive to June 9. General manager Jeff Luhnow said the team doesn't expect this to lead to a "long absence" for McCullers but didn't specify a specific timetable for his return.
"It's something that was going to keep him from making his start [Tuesday]," manager A.J. Hinch said. "So then we decided to put him on the DL and give him complete rest and hope that he comes back at the end of those 10 days."
In Monday night's loss to the Texas Rangers, the Astros suffered another injury. Right fielder Josh Reddick crashed into the wall while trying to make a catch on a ball hit by Joey Gallo and was taken out of the game to start the fourth inning.
Hinch said Reddick complained of a small headache and was evaluated and sent home before the game ended. He was diagnosed with a mild concussion and will be re-evaluated on Tuesday.
McCullers joins ace Dallas Keuchel and right-hander Charlie Morton on the 10-day disabled list. Houston has also been without starter Collin McHugh, who is on the 60-day disabled list, all season. There was some good news for the first-place Astros on Monday, with right-hander Joe Musgrove coming off the disabled list to start against the Texas Rangers.
McCullers is 6-1 with a 2.58 ERA in 13 starts this season, providing a potent 1-2 punch with Keuchel at the front end of the rotation as the Astros raced to a double-digit lead in the AL West.
The injury to McCullers forced Houston to shuffle its lineup. Brad Peacock will pitch in his spot Tuesday against the Rangers on three days' rest. The Astros decided that Peacock was the best option to slide into that spot, even though he left his previous start after struggling early.
Hinch said he would normally be reluctant to have a pitcher make two starts so close together, but several factors made Peacock the best option in this situation.
"With Peacock, it's a little bit different," Hinch said. "He's got some experience as a reliever. He also came out of the game after three innings and pitches in the 70s the other day. So of the time to send a guy out after three days, this is probably the best-case scenario."
The Astros will put top prospect Francis Martes into the rotation to make his first major league start on Wednesday. Martes allowed four hits and four runs in 3 2/3 innings of relief Friday in his major league debut.
Although dealing with the mounting injuries to his pitching staff has certainly been challenging for Hinch, he and the Astros aren't feeling sorry for themselves.
"We can make it work," Hinch said. "I think everybody wants the frustrating quote or the 'woe is me' or 'the sky is falling.' The reality is we've got a really good team, and we're going to have to absorb this or else. So I think our guys understand exactly what's going on. There's no more pressure on us. There's no more anxiety on us ... we're tough enough to deal with it."