[DarthMonk]

From When Pride Stll Mattered:

The pros, for their part, were more surprised than pleased in their initial impressions of Lombardi. They considered him a college chump. –snip- For offensive linemen, Lombardi taught rule blocking, another technique used at West Point. Instead of blocking a specific defensive player, each lineman blocked a zone, and if there was no one in that zone he fanned back to another area, following specific rules, hence the name. Army and other schools were ahead of the pros in using rule blocking. It eventually became the norm in the National Football League, but the Giants had difficulty adjusting. “You had that first July that they didn’t believe,” Lombardi said later. “When I first explained it they looked at one another –- ‘What’s he doing?’”

In the case of zone blocking as a concept (if not in name), Vince Lombardi may not have invented it, but he certainly was the first NFL coach to detail it – in actual practice and in writing after the fact. Lombardi’s Packers were known above all for the power sweep, but in the posthumous book Vince Lombardi on Football, the “Do-Dad” block was explained in great detail. The alpha dog of NFL coaches detailed it this way:

The guard and the center do-dad, or area-block, the defensive tackle and middle linebacker. Do-dad blocking is used against stunting lines or lines that stack one defender behind the other. In the case where the defensive tackle has the inside charge and the middle linebacker is keying the fullback and has the outside responsibility, the middle linebacker will, with the snap of the ball, move immediately to the hole, making it impossible for the center to cut him down because of the middle linebacker's key on the fullback. In this case, we will use do-dad blocking.

The center is the lead blocker -- the apex. He will lead-step, the same technique as for the down block, for the crotch of the defensive tackle. The offensive guard, using the same technique as he does in the drive block, will aim for a point which is outside the defensive tackle. If the defensive tackle has an inside charge, the guard immediately releases the tackle, picking up the middle linebacker who would be moving with the key of the fullback toward the hole. The center, since the tackle is moving into him, would pick him off.

DarthMonk