Darnold found himself on the injury report headed into Week 10, with Mehta reporting the rookie had a "significant foot strain."
With the team at 3-6 and in third place, it was clear that the situation called for caution.
"We don't want to rush things," Darnold said, according to ESPN's Rich Cimini. "That's one thing we don't want to do. Yeah, I'm eager to get back out on the field with my guys, but at the same time, I have to take care of my body, first and foremost."
The third overall pick in this year's draft, the 21-year-old Darnold became the youngest quarterback in NFL history to start a season opener. After that, he played in every snap through the first nine games before getting banged up.
Darnold has completed 55 percent of his passes for 1,934 yards, 11 touchdowns and 14 interceptions this season.
For now, though, his focus has to be on getting healthy and then getting back on the field with his teammates. As he previously noted, his long-term health has to be the No. 1 priority.
Without Darnold available, the Jets would have to turn to McCown, who went 5-8 with New York in 2017.