FLORHAM PARK, N.J. — Shortly after the Jets chose a quarterback out of the University of Southern California with the third overall pick in April’s N.F.L. draft, the team’s incumbent at the position, Josh McCown, received a text from his oldest daughter, Bridget.

“He’s less than a year older than me,” she said. “Crazy.”

The 39-year-old McCown could only chuckle. He would still fight to earn the starting job for the Jets for a second straight season, but this year, he would lose that battle.

The Jets’ brain trust has decided it simply cannot wait to anoint its most promising quarterback prospect in 50 years. At 21 years 97 days old, Sam Darnold will become the youngest quarterback to start an N.F.L. season opener since 1970, and the second-youngest quarterback ever to start a game. Only Tommy Maddox, who filled in for the injured John Elway of the Denver Broncos in Week 11 of the 1992 season, started at a younger age (21 years 81 days).

This, of course, is a different time, a different city, a different, more desperate franchise. The Jets have drafted four other quarterbacks in the first round since Joe Namath in 1965. It has not gone well. None could ultimately match what Namath did once: win a Super Bowl.