"Obviously Ben's experience Sunday night, I think we all knew the facts going into it, the speed of the game, the challenges that were presented to him," McCarthy said. "I just felt with the opponent that we're playing, we need some more experience at that position."
Gilbert and Rush have never started a game and have combined to throw nine passes in their careers, but their experience in the league -- Gilbert has been in the NFL off and on since 2014, Rush since 2016 -- gives them an edge over DiNucci.
"Garrett Gilbert has been here for a couple of weeks. He's had a chance to play in preseason games and just has more experience," McCarthy said. "And no different with Cooper. Cooper played last year, very familiar with the system. [Offensive coordinator] Kellen Moore has a lot of confidence there. So we're going to go through the week and then make a decision."
The Cowboys are moving to their fourth starting quarterback -- and third in four games -- after Dak Prescott suffered a right ankle injury that ended his season Oct. 11 and Andy Dalton was put on the reserve/COVID-19 list Tuesday.
Dalton was unable to play against Philadelphia because of a concussion suffered Oct. 25 against Washington.
McCarthy hopes a decision on Gilbert or Rush, who was Prescott's backup from 2017 to 2019 and was released in the offseason, can be made before Saturday's practice. The Cowboys will have a lighter practice Wednesday before going through a full-padded workout Thursday that goes longer.
This will be the first time since 2015 that the Cowboys have started four different quarterbacks in the same season. That year Tony Romo, Brandon Weeden, Matt Cassel and Moore were needed, and the Cowboys finished 4-12.
McCarthy started four quarterbacks in 2013 with Aaron Rodgers, Seneca Wallace, Scott Tolzien and Matt Flynn. The Packers finished 8-7-1 and made the playoffs. Tolzien and Wallace are now Cowboys assistants.
McCarthy said this is the first time he has had an open competition for the quarterback job during a practice week. His experience in Green Bay after Rodgers suffered a broken collarbone could help McCarthy.
"At the end of the day, every position room is designed to get the guys ready to play, whether it's the offensive line room and there's changes in there or defensive line room and changes in certain players potentially getting more reps in the game," McCarthy said. "It's obviously heightened in the quarterback room not only because of the responsibility of the position but because of the design of our room. There's definitely are things you learn from, play design, game-planning process and playcalling thoughts. These are all part of our game plan weekly conversations."
As for Dalton, McCarthy said the veteran is "doing fine," and if he progresses through the COVID-19 protocol, he could be back around the team at the end of next week. The Cowboys have their bye week after the Steelers game.