The single most basic rule of zone blocking is that you block the first person to cross your face. To start off, we will set up a basic strong right formation with a single back, BA's favorite. The defense will be lined up in a very basic 3-4 alignment. For now, I will focus on the goal of this blocking from an offensive lineman's point of view. I do intend someday to describe the defense's responsibility in another writeup.
We are going to be running a simple dive play to the strong side. This run is designed to go between the strong guard and strong tackle. This is a very quick-hitting run play and basically will be straight up as far as action from the running back and qb. When the QB gets the ball, he practically has to run to get the ball to the back as soon as possible so he can hit the hole hard.
So to start off, both tackles and center are covered with down linemen. Their assignment is the easiest, as all they have to do is block heads up for now. As soon as the ball is put into play, they take one step in the direction the play is running (in this case, to the right). The center is to attack the nose tackle's right shoulder and try to drive him. If done successfully he will be coming off this block soon. The strong tackle will be attacking him heads up for now.
This is why zone blocking requires you to have very agile guards on your team. Both guards' primary responsibility is to step right just like the rest of the line and get a hand on the men that are lined up heads up on the center and tackle, effectively double teaming the two linemen. Now these blocks will only last maybe a half a second to get momentum going in the favor of the offensive line.
The center now has one job at this point in time -- get off the nose tackle and block the backside linebacker. This is the reason for attacking the outside shoulder at the point of attack -- to allow the guard enough time to get his butt around to basically wall off the guard. We call this type of block a combo block. It effectively gives us the best angles. The strong guard makes his move to "double" the man heads up on the strong tackle. This is mainly to ensure that the strong tackle doesn't give up the inside, but again this block should be all of half a second to help the tackle and then his job is to release and block the strong side linebacker.
This is effectively a great running play if everything goes the way its designed. The first person unblocked to make a play is a corner or safety down the field. Now there is something else that happens on a play like this. A good defense will respond to these type of actions like attacking the outside shoulder or maybe you just get a good read from a linebacker, but that is why in Part 3 we are going to discuss the "cutback." Stay tuned.