"He's starting to get agitated when he doesn't make his pitches, which means he's closer and closer to being back to form," Hinch said. "He's a pretty big perfectionist out there, and if he's doing that in his bullpens it's a good sign."
Feldman has been on the disabled list since May 27 with a torn medial meniscus in his right knee. The righty threw to stand-ins Jake Marisnick and Preston Tucker from both sides of the plate, with Hinch, trainers and ace Dallas Keuchel observing behind the cage.
Speaking to reporters on Friday, Feldman said his arm is slowly getting back into shape.
"That part of it has been feeling good," Feldman said of throwing off a mound. "Trying to keep my arm in as good a shape as I could, even when I couldn't move around too well, still throwing at least. Shouldn't be playing too much catch-up on the arm end of things, it's more about getting my leg into shape to field my position a little bit."
Hinch said he has no timetable for Feldman's return, though Feldman will start to intensify his workouts and throw a live batting-practice session soon.
Feldman, though, thinks the latest developments are inching him back into the Astros' pitching fold.
"Throwing off the mound is definitely a step in the right direction," Feldman said. "Just trying to stay positive and upbeat and I can kind of see the light at the end of the tunnel a little bit. Makes it a little more satisfying to know that I'm closer to getting back than I have been at any point."
• The Astros scratched center fielder Colby Rasmus about two hours before Saturday's game with a skin infection. George Springer slid over to center and Domingo Santana was inserted in Rasmus' spot in the order and played right field.
Chandler Rome is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.