That's part of recognizing the coverage. Are all 3 down linemen rushing? Did X come on a blitz? If so, who is covering for X and from where? Was it man or zone? If man, where is the safety and have you looked him off your primary?

The QB should also know what routes his WR's were running and therefore how the defense, given their alignment, most likely reacted. Did a safety come up to cover the short routes, or did the LB's slide over?


So, if the QB knows all of that (and more, as that was in no way an exhaustive check list), then he can look at some other route right up until he needs to throw (or not throw) to his primary. And he has to decide instantly so he doesn't give the defense time to react to his eyes, but instantly he needs to decide does everything look like he expected it to? If so, release the ball.


Young QB's who haven't yet mastered reading a defense will simply stare down their primary, hoping he can see his primary get open rather than helping him to do so. And you wind up with Kai Nacua intercepting Finley 3 times.