Davis said on Wednesday that it might be a game-day decision, but he changed his mind when Kelly Holcomb's injury problems didn't improve fast enough.
"He (Holcomb) didn't make enough progress today to warrant (playing)," Davis said. "I'm a firm believer that unless you can take a lot of the work, you miss the timing and you miss the game-planning installation.
"Kelly has been in the league long enough that you would suspect he could grasp everything if he was physically capable of doing it, but there's too much uncertainty to be able to ascertain what degree of physical health he'll be on Sunday."
Couch admits that this could be the chance he needs to restart his career. At the same time, he's trying to keep his focus on Sunday's game.
"I just want to go in and get a win," Couch said after Thursday's practice. "Whatever happens after that has yet to be determined. All I'm worried about is the near future."
Couch hasn't played in a regular-season game since he suffered a broken fibula in the regular-season finale last year against Atlanta. He officially lost his job to Holcomb two days after the second preseason game.
While Couch has remained a team player during his stay on the sideline, there's no doubt that it has been difficult for him to stand and watch.
"This is about as low as it can get, being the number one pick in the draft and not being able to get into the game," Couch said. "It can't get any worse for me. That's a good thing because I can handle anything that will come at me in the future, and I'll be a stronger person."
Couch maintained throughout training camp that he was throwing the ball as well as ever. He feels that's still the case.
"All during training camp I felt I was playing better than I was a year ago," Couch said. "I feel healthy and obviously well rested. I feel like I can go out and be really effective.
"It's always frustrating. Being on the sideline you always want to be in the game. But I'm always supportive of Kelly. You have to stick with the guy that you chose. He was able to come back and pull the game out at the end, and it was good to see him do that."