Now consider the restlessness of Petty, who graduated from high school in 2009, the same year as Smith. Petty, who lost some practice time after bruising his right shoulder in early September, might not have been a better option than Smith this weekend. But Coach Todd Bowles recently said for the first time that Petty’s opportunity might be coming soon.

Until then, Petty, backup to the backup, will keep quietly waiting.

“There’s a plan and a purpose for everything,” Petty said.

Patience, he said, is not always an easy thing for a quarterback.

“When you’ve been a starter since you were a seventh grader, and now you’re in a locker room with guys who are in their 30s who have been in this league for a while, it’s tough to handle that mental aspect of it — not being the guy,” Petty said.

This is a topic he often discusses with the rookie Christian Hackenberg, who started as a true freshman at Penn State, playing his first college game at MetLife Stadium. Now Hackenberg is the last-string quarterback for the only team in the N.F.L. with four quarterbacks on its active roster.

Petty has learned, too, how to channel his frustration into a desire to learn as much about the position as possible. At Baylor, Petty redshirted, then grayshirted, then became mired behind Robert Griffin III and Nick Florence for two seasons. When it was finally his turn, Petty took off. He threw for at least 300 yards in his first seven games, with 18 touchdowns and only one interception.

“There was an appetite there that maybe if I had started as a sophomore or freshman might not have been there,” Petty said.