Paging any X's and O's types here on the boards...
So, I know only the basics of the zone read (I know that the QB is reading the backside DE - if he crashes, keep, if he sits, give), but I'd like to brush up a little bit so I can better understand it during this season.
So it seems like whenever I see the play run, the DE doesn't observe the tidy little dichotomy of crash vs. sit like he does so obediently in NCAA 11. That is, he never just stands straight up and waits to react to the QB, but instead he usually fires out of his stance in some direction. My question is: what exactly is the QB reading on the DE? Is he looking to see if his first step is downfield vs. lateral? That seems like a subtle, hardly perceptible thing to judge in a split second. Is there a more concrete threshold that our QBs are looking out for? Like, say, does the QB only consider it a crash if the DE winds up on the inside shoulder of where the backside OT was pre-snap?
Follow-up question: If the QB does keep the ball, he sometimes (always?) has a third option with the bubble screen on the backside. What should the QB be keying on in this situation? The backside safety? The corner over the bubbling WR?