I wrote this up in abbreviated form originally for my breakdown of the OU-Texas game for Yahoo!’s Dr Saturday, but this is something I’ve been thinking about for awhile. There is still way too much confusion about inside zones and outside zones. Part of this is that there are a lot of coaching points on these plays. Indeed, many NFL teams run nothing but inside and outside zone and maybe “power” and “counter,” and therefore spend hours every week coaching the finer points of these plays. But that’s not a reason why the basics have to be so confusing. So here is an imperfect but very basic explanation for what zone runs are, and the difference between inside and outside zones.
Think of this as Newtonian physics for the run game. Yes, Einsteinian physics is more precise and is necessary if you want to understand certain extreme events, but Newtonian physics is extremely useful, easy to understand, and will explain pretty much all you need to know unless you’re currently an offensive line coach (and even if you are, my hope is that this is a pretty good reminder of some things.) Here goes:
On zone plays, the linemen keep the same blocking schemes, regardless of how many tight-ends or wide receivers they use. The aiming point for the runningbacks remain about the same. Many zone teams begin by focusing on the outside zone. Once that is established and the defense is flowing fast to the sideline, the offense comes back with the inside zone.
Yet there is much discussion of what “zone runs” even are. First, there is only so much “zoning” in a zone — much of it is still just blocking the guy in front of you. On all zone runs, the linemen must ask, “Am I ‘covered’ (is there a guy directly in front of me, aside from a linebacker set back a few years)? Or am I ‘uncovered’ (there is no one directly in front of me)?”
If “covered,” there is very little “zoning” at all: The lineman’s job is to block the guy in front of them. Fans, commentators, and even coaches often overcomplicate things. The “zone” aspect comes in with “uncovered” linemen. If “uncovered,” the lineman must step “playside” — i.e. the side the run is going to — and help double-team the defensive linemen along with his “covered” cohort. Once the two of them control that down defensive lineman, one of the offensive linemen slides off to hit a linebacker. It’s not that complicated. Indeed, let’s say the five offensive linemen are covered by five defensive linemen. In that case, each guy (save for maybe the backside offensive tackle) will just block the guy in front of them — there is no “zoning” at all.
It gets a little trickier regarding the difference between inside and outside zones, though this involves technique, not assignment. (And this is where the rabbit hole begins, as there are a zillion coaching points to doing this well, but that is better discussed in a coaching DVD rather than this overview.)
On outside zone plays, the offensive linemen take a bit more of a lateral first step and try to reach the defender across from them. He wants to get his body between the defender and the sideline. It’s important to note, however, that the very act of trying to reach the defender often gets him flying to the sideline, at which time the offensive lineman can then switch to driving the defender to the sideline. The runningback aims for a point outside the tight-end, though he can cut it upfield wherever a seam appears.
Once the defense begins flowing too fast to the sideline, coaches typically dial-up the inside zone. The rules are the same — covered and uncovered — except this is more of a drive block as the aiming point for the runningback is inside. The play often results in a cutback if the defense is flowing fast for the outside zone, but the difference between the outside zone is one of technique, not assignment. And, again, it does not make a difference to the linemen (or at least not much of one) if OU runs this from a four wide set or a two-back one.
On the inside zone the runner aims for the outside hip of the offensive guard. Now, his read can vary by team. Some teams have him read that three technique defensive tackle, while others have him read the middle or “Mike” linebacker. In both cases the idea is for him to find the “vertical” crease — either straight playside off the guard’s hip or backside on a cutback.
A few concluding thoughts. There’s obviously more to it than this. The biggest thing offensive line coaches work on is the initial steps for their linemen (often called a “lateral” or even slightly backwards “bucket step”), and later they work diligently on the proper technique for double-teaming a lineman and then getting up to the “second-level” to block a linebacker. But again, if a defensive “covered” all the linemen, there is no zone. It still comes down to blocking the guy in front of you.
Finally, there are variances. One is the “pin-and-pull” variant of the outside zone or stretch play run by the Indianapolis Colts. Also, for additional reading check out these posts from Trojan Football Analysis on (old-school) Nebraska’s inside and outside zone plays.