Hinch said Sunday it is unlikely McCullers, who is 10-6 with a 3.93 ERA this season, would be able to rebuild his stamina to the point where he could start.
"I guess never say never cause once you get on the mound and get going things can progress a different way, but I think the focus will be and probably should be shorter stints," Hinch said.
McCullers has been on the disabled list since Aug. 5, one day after he left a start against the Los Angeles Dodgers early because of a muscle strain.
Hinch also said McCullers' rehabilitation program was being slowed down because of a "continued lack of progress,'' but he is still targeting September for him to resume throwing off the mound.
"We knew it was September until we were going to consider doing anything. Then we thought we could be a little bit more aggressive with him, but we're going to put that on pause and just have him do a throwing program,'' Hinch said.
"He's feeling pretty symptom-free. I think his throwing has been fine, but kind of the re-evaluation of him, we've decided to push it back.''
Hinch is not sure how he will structure his rotation down the stretch without McCullers. Left-hander Framber Valdez could be an option to start after allowing one run in 4 1/3 innings to earn the win in his major league debut at Seattle on Tuesday. The Astros could also take advantage of September call-ups to address the vacancy.
"As the rules change where we can expand the rosters, you could see a spot going to somebody that steps up and takes the ball and is very reliable for every five days. You could see that spot change. You could also see us be creative with the bullpen and have a bullpen day every now and then,'' Hinch said.
But Hinch is wary of being too experimental given how closely contested the AL West is.
"We've got to continue to put really good pitchers out there and not be too much trial and error because of the race that we're in, but I could see it being used a lot of different ways. My preference would be for somebody to step up and throw the ball very well and have our normal rotation,'' Hinch said.