During football season a few years back, Scott Chadwick, a high school coach in North Carolina, had a Sunday night ritual as practical as it was peculiar. Every week, he would scan the list of N.F.L. players injured that day, hoping that no quarterbacks were seriously hurt.
He knew that the repercussions of a broken wrist in Minneapolis or a torn ligament in Seattle could reverberate all the way to Waxhaw, N.C., outside Charlotte, where Chadwick’s staff at Marvin Ridge High School included the most overqualified quarterbacks coach in the Southern Carolina Conference.
That coach, Josh McCown, had turned an unplanned hiatus from the N.