Inside zone blocking rules allow linemen to use the movement and attack angles of the defenders against them. Whichever way the defender chooses to go, he is sealed off and the running back is prepared to cut off the block. Nebraska running backs are taught to attack the line-of-scrimmage (LOS) before cutting on inside zone plays. This gives the blocks the needed time to develop. The rule for the I-back is that his feet must replace the feet of the lineman before he can cut.
Inside zone blocking rules are keyed by whether a lineman is covered or uncovered. A covered lineman (one who has a defensive lineman aligned across from him) will execute a "stretch base" technique. This means he will take a short stretch step to the play side (step right on a 44, left on a 46) and attempt to control the playside shoulder of the d-lineman. The purpose of the stretch step is to invite movement by the d-lineman, then immediately engage him.
Uncovered linemen (no d-lineman across from them) execute a "stretch double" technique. Stretch double also calls for a stretch step to playside. The uncovered lineman then attacks the backside shoulder of the same d-lineman, creating double teams on most of the defensive linemen.
NOTE: the linemen operate on a system that moves to playside, NOT toward the hole called. On a 44 dive the play is called to the right guard, but the key is that it is a right side play. The right tackle's and right tight end's playside shoulders are their RIGHT shoulders even though the play was called to the left of them. The 4 hole is to the right side of the center, so right is playside for everyone on the line.
In executing the stretch double technique, the uncovered lineman assists the covered lineman to the playside; i.e., if a center and playside tackle are covered, the playside guard executes the stretch double with the tackle, NOT the center. If side-by-side linemen are both covered, the playside lineman is "on his own," and executes a stretch base block without double team help.
When executing the double team, both linemen follow what some coaches call a four hands-four eyes technique. This means they have four hands on the defensive lineman and four eyes on the linebacker in the area (their zone- which is where the name of the blocking comes from). When that linebacker commits to attacking the LOS one of the linemen chips off the double team and blocks him. The other lineman must be in position by then to take over the block on the lineman by himself. The linebacker is technically the responsibility of the uncovered lineman, but in practice either lineman can chip off and take the linebacker, depending on their position.
The goal of the stretch and stretch double is to create a cutback lane for the running back. When executed correctly, the "stretched" defender has moved in the direction of the call, and the stretch double prevents him from reaching a running back that has "cut back" against the flow of the play. If the double team can prevent the down lineman from making the tackle, and the "chip off" block prevents the playside linebacker from doing the same, the play can quickly get into the secondary.
The beauty of zone blocking is that the defense can pick its poison. Which ever way they choose to attack or stunt, the linemen (if they have perfected the zone blocking teamwork) can account for them. And the running back is trained to watch this block develop and cut off of it, no matter which direction the defenders are moved.
A very important block on an inside zone play is the backside seal block that allows the IB to cut back all the way to the backside TE spot if the whole defense fights to the playside. Depending on the formation used, the backside tackle, tight end, or fullback can be used to block the backside. A sure sign of an inside zone play is when the fullback heads away toward the TE without a fake while the IB goes straight ahead for a handoff. In one-back sets the backside seal cen be done by a wingback in motion. This is one area where big WB Troy Hasselbroek shone at the end of the 1999 season.