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Chip Kelly offense 101: Inside run game

The first part of our in-depth look into Chip Kelly's offense breaks down his two primary inside run plays: inside zone and power.

"I’ve said it since day one: We don’t do anything revolutionary offensively."

Despite his reputation as an innovative offensive mind, new 49ers head coach Chip Kelly has long maintained that there’s nothing groundbreaking about his offense. "We’re not doing anything that’s never been done before in football," Kelly told media members during his second NFL training camp.

So if Kelly is not, in fact, attempting to fundamentally change the game of football with his schemes, what exactly does he do offensively?

That’s the question we’re aiming to answer over the next couple of weeks by breaking down the various aspects of Kelly’s scheme. There are a number of misconceptions about his offense floating about the football Internet. To borrow Trent Baalke’s favorite new phrase, we want to separate perception from reality, beginning today with the inside run game.

Kelly’s offense has a reputation for finesse. Philosophically, however, Kelly’s attack has more in common with Jim Harbaugh’s power run game than many would like to believe. The how might be different, but the why is the same. Harbaugh packs the box with fullbacks, tight ends, and extra offensive lineman so that he can run the ball down your throat; Kelly spreads the defense out with multiple wide receivers so he can do the same thing.

Inside Zone

The foundation of Kelly’s run game — or perhaps more accurately, his entire offense — is the inside zone. "The inside zone play is our ‘go-to-work’ play," Kelly said at a coaching clinic in 2009. "It has become our signature play. We want to get off the ball and be a physical, downhill-running football team. This is not a finesse play."

Finesse is a common label attached to the zone-blocking scheme, which forms the core of Kelly’s ground attack and contributes to his offense’s reputation for lacking the sort of toughness typically associated with man-blocking, or gap, schemes. After all, zone blocking has to be a little soft if the other prominent blocking scheme garnered the name "power," right? Well, not exactly.

At its most basic, the inside zone is about creating double teams, driving defenders backward, and getting vertical push up front. The "zone" facet of the play is simply the structure for how offensive lineman will determine which defender to block. How much "zoning" is actually required on the play is determined by the alignment of the defense.

Offensive lineman begin each play by asking themselves one question: Am I covered or uncovered? If covered — meaning there is a defender directly over them — "zoning" effectively goes out the window. In most cases the lineman will still step to the play side (i.e., the direction the run is going) initially, as is customary on zone runs, but his job is to simply drive the man in front of him backward. If uncovered — meaning no one is aligned directly over them — they will step to the play side and look to create a double-team with the adjacent lineman.

Creating those double-teams is a big part of the why behind Kelly’s affinity for the inside zone. It’s physical football that aims to "knock the crap out of the defender, and deposit him in the linebacker’s lap." This is the identity Kelly wants his offenses to possess.


In Kelly’s version of the inside zone, the process of determining who is blocking who begins with the center, who identifies the point, or zero, defender. The rule for identifying the point defender is simple: It’s the A-gap defender to the play side. So if the call is an inside zone to the right, the center will pick out the defender aligned in the gap to his right side. The responsibilities for the other four lineman fall into place from there, with the guards handling the No. 1 defenders to either side of the point defender and the tackles handling the No. 2 defenders.

Because of the spread formations Kelly deploys, there are rarely more than six defenders in the box to defend against the run (or seven if he opts to keep a tight end inline). Combined with the up-tempo pace his offense features, this defines the look of the defense for the offensive line, making it easier to identify the point defender and set the blocking scheme. There’s no need to identify the specific front the defense is showing, the offensive line only needs to count defenders. As Kelly put it, "if the offensive line can count to six, you have a shot to run this play."

If there are only five defenders in the box, it’s an easy scheme: one offensive lineman for every defender.

If all five of those defenders are up near the line of scrimmage, there is no zoning involved. Each offensive lineman will simply block their respective defender based on Kelly’s number system. If one or more of those defenders are off the line of scrimmage, the offensive line will create double teams where appropriate, controlling the defensive lineman first before moving off to the linebackers.

"We must secure the down lineman before we think about coming off on the linebacker," Kelly tells his players. "If the linebacker is within an arm’s length of the block, [the offensive lineman] can come off. Never disengage from a double-team block and have to run to get to the linebacker."

If the defense starts dropping an extra defender in the box to slow down the run — something that happens on the majority of plays — Kelly has a few answers to account for that free defender.

The primary answer is also the most contentious: the zone read. "If the defense is a six-man box, the quarterback is responsible for the sixth man in the box," Kelly said during his clinic talk back in 2009. "He reads the defender and controls him. The quarterback is blocking that defender. He cannot physically block him because that is a mismatch. What he does is run the ball if the defender attacks the running back. He makes the defender respect him as a runner and keeps him out of the play."

The zone read as Kelly runs it is not a tactic to create rushing opportunities for his quarterback. Rather, it’s an extension of the blocking scheme that flips the numbers advantage in the box from the defense to the offense. As Kelly explained to his clinic audience, "We want the ball in the running back’s hands. We do not want the quarterback carrying the ball. The option can put the ball in his hands, but the defense can force it out of his hands. We want the quarterback to give the ball unless he cannot."

Like many facets of Kelly’s offense, the zone read has a mathematical idea behind it. In a more traditional run scheme, where the quarterback is not a threat to run the ball, the defense can always put one more defender in the box than the offense can block to gain an advantage. By effectively making the quarterback a blocker without having to touch a defender, that advantage flips back to the offense. The defender who was once unaccounted for is put into conflict — Do I attack the running back or the quarterback? — and made wrong on every play.

The zone read is just one variation of Kelly’s inside zone scheme. I’ll be covering many of the others in separate posts, but I wanted to focus on just the basics here. What makes the concept so appealing, and why it serves as the foundation for Kelly’s offense, is that it is simultaneously simple and flexible.

The inside zone’s simplicity makes things easy and defined for his offensive lineman, an important consideration when utilizing the up-tempo pace Kelly prefers. But it’s also flexible enough to "dress up" with numerous variations that provide answers to the many problems defenses can create, all without changing the responsibilities of the offensive line. "If they can run the offense with any scenario they may face, you will be successful in running the ball," Kelly said at the 2009 clinic. "If they have all the answers to the problems the defense may give them, they will be good."


Kelly’s other bread-and-butter inside run is one that should be familiar to 49ers fans, as it was the team’s hallmark under Jim Harbaugh: the power play. As you can probably imagine, Kelly’s version differs just a bit, but the core principles are the same.

Power aims to accomplish two basic goals: 1) use the leverage created by down blocks to create movement at the point of attack and seal off the back side; and 2) outnumber the defense to the play side by pulling an offensive lineman from the back side to lead the running back through the hole.

One problem teams must account for when running out of the shotgun is the tendency to tip the direction of the play based on the running back’s alignment. For example, with the inside zone, if the running back is offset to the quarterback’s left side, the run is designed to hit to the right side of the offensive line (It's always possible that the run could cut back left, but the offensive line and running back's initial aiming point are both to the right). Defenses know this, of course, and will often cheat toward the side opposite the running back.

Kelly runs power in a manner that makes it an ideal complement to the inside zone by taking advantage of the defense that begins to cheat. In Kelly’s version of power, the play hits to the same side as the running back’s initial alignment. This adds a misdirection element that, combined with the down blocks, makes the start of the play look a lot like inside zone. The difference comes once the back takes the handoff. At that point, he bends the run back the other direction, getting in behind the pulling guard through the hole.

Neither inside zone or power are unique offensive concepts; nearly every team in football has some version of the two runs in their playbook. The window dressing Kelly uses to disguise these plays might be different than the way many NFL teams approach it, but these are old-school, time-tested football concepts that were in the league long before Kelly arrived. And it’s those proven concepts, not "gimmicks," that lay the foundation for Kelly’s offense.