It's essential for him to stay composed, even if he just took a hit from a blitzing linebacker, because a technician in the booth switches off the headset when the clock hits 15 seconds. That's why you have to study. You have to keep your nose in the book, so, when things start happening, it's second nature to you. You have to know exactly what to do. A quarterback has to know where everybody is supposed to be on every play.
Football coaches talk in a funny language.
With the clock running between every play, they can't afford to waste any words. In coach-speak, X and Z are wide receivers and Y is the tight end. The 2 hole, for instance, is between the center and right guard, and the 4 hole is between the right guard and right tackle. That's why you have to study. Every word, color, and letter mean something.