All they know is that if it is, Rush has left the Cowboys in a better spot than when he took over for an injured Dak Prescott three weeks ago.
"I can't say enough about his play," owner and general manager Jerry Jones said after the Cowboys' third straight victory. "What it has possibly done for this team this season to give us a chance to sit here after these last three ball games and maybe have the opportunity we've got for the rest of the year. It's amazing. It's far more than what I would've expected."
Prescott is eyeing a return next week against the Los Angeles Rams, sources told ESPN's Adam Schefter, while the Cowboys (3-1) want to make sure that Prescott is as close to 100% healthy as possible and could push back his return until Week 6 against the division-rival Philadelphia Eagles.
After the win over Washington, Jones said, "I can't give you anything there medically" about the status of Prescott, who had surgery Sept. 12. Prescott had the stitch removed from his right thumb on Monday, and coach Mike McCarthy said during the week the quarterback still had some swelling in the thumb that needed to subside before he could step up his throwing.
"I really don't know that I'd call that throwing what he's doing, but he's certainly got movement," Jones said. "I wouldn't know if he's throwing at a level that you could say the grip and everything effectively is a good throw, a good, normal passing throw."
Rush became the first quarterback in Cowboys history to win the first four starts of his career and the first in the NFL since Kyle Allen won five straight for the Carolina Panthers over two seasons (2018-19).
"It's been fun. Trying to enjoy it," Rush said. "The NFL doesn't let you enjoy it much. You got to go week in and week out and play. The 4-0 is just, I mean, I guess I would say the defense and all the breaks you catch, it's just kind of lucky. QB win stats, they are what they are. It's a team game."
Rush completed 15 of 27 passes for 223 yards with two touchdown passes on Sunday. He has been sacked just twice in his three starts and he has not had a pass intercepted.
While Jones said he would love to have a quarterback dilemma because it would mean Rush has won games in Prescott's absence, Prescott will return to his starting role when healthy. Now, it's just a matter of when.
"You just enjoy playing ball," Rush said. "You don't get to start every week as a backup. That's why when you're in there, you just want to do your job. You really enjoy it. It's fun being with those guys. We have a heckuva team. Great locker room. So you cherish it all. When your number's called, you just keep playing."