Dalton was placed on the reserve/COVID-19 list on Tuesday, which will knock him out of Sunday's game against the Pittsburgh Steelers, according to multiple sources.
Dalton did not practice last week as he worked through the concussion protocol, but he was in some team and quarterback meetings later in the week. He did not fly with the team to Philadelphia because he was officially ruled out the day before kickoff.
Dalton has started the self-quarantine process, and the Cowboys have begun contact tracing, but no players on the trip tested positive before the Philadelphia game and Monday's tests were negative as well. A source also told ESPN's Ed Werder that there were no positive COVID-19 test results Wednesday.
Rookie Ben DiNucci started in the 23-9 loss to the Philadelphia Eagles. He completed 21 of 40 passes for 180 yards, was sacked four times and lost two fumbles, including one that was returned for a touchdown. Garrett Gilbert served as the No. 2 quarterback last week, and the Cowboys added Cooper Rush to the practice squad last week. Rush has completed the COVID-19 protocols.
There is not a definitive plan yet as to who will start Sunday against the Steelers.
According to a source, the plan is to work Gilbert and Rush during the week with the first team, although DiNucci has not been ruled out even though he struggled against the Eagles and would face a more difficult defense in Pittsburgh.
"I think that it was a lot for him," owner and general manager Jerry Jones said on 105.3 The Fan in Dallas before the Dalton news. "I think we, certainly, as a team, paid the price to have him come in and under those circumstances. And that's almost trite. It was frankly more than he could handle. I don't know what you could have expected for somebody to come in under those circumstances."
Gilbert has been able to practice for just two weeks since being signed off the Cleveland Browns' practice squad. He has completed just 2 of 6 passes for 40 yards in six appearances with the Carolina Panthers and Browns.
Rush served as Prescott's backup during 2017-19 but saw only mop-up action, completing 1 of 3 passes for 2 yards. He was released in the offseason after the Cowboys drafted DiNucci. He had been with the New York Giants and had been on their practice squad until Sept. 29.
Rush has the most familiarity with the Cowboys' offense, and coordinator Kellen Moore and quarterbacks coach Doug Nussmeier have the most familiarity with him.
If either Rush or Gilbert starts against the Steelers, it will be the first time the Cowboys have had four different starting quarterbacks since 2015. Tony Romo, Brandon Weeden, Matt Cassel and Moore started for the Cowboys, and they finished that season with a 4-12 record.
Dalton started two games after taking over for Dak Prescott, who is out for the season with a right ankle injury, before taking a hit from Washington Football Team linebacker Jon Bostic in the third quarter of a 25-3 loss. Bostic was fined $12,000 by the NFL for the hit.
Dalton has completed 52 of 85 passes for 452 yards with one touchdown and three interceptions in four appearances. The Cowboys have scored one touchdown in their three games without Prescott and none the past two games. It's the first time in his head-coaching career Mike McCarthy has presided over an offense that has failed to score a touchdown in consecutive games.
On Monday, McCarthy was asked about the Cowboys not having any players placed on the reserve/COVID-19 list during the regular season. In training camp, wide receiver Jon'Vea Johnson and cornerback Saivion Smith were on the reserve/COVID-19 list, although Smith's test was a false positive.
"It's part of the team meeting messaging," McCarthy said. "Pretty much almost every day or definitely a couple times a week there's always feedback that our football operations is giving us as far as what the new emphasis is and how we can continue to improve on it, and I think our players and staff have done a very good job, the best they can, as far as the social distancing and the tracking and all the components that go into it. So hopefully we can keep it going."