The I-Formation: Offensive Bread and Butter

By Michael David Smith

Offensive formations are rapidly evolving, with three-receiver sets, four-receiver sets, and multipurpose backs who can line up anywhere and catch the ball as well as they run it. But the way Pro Bowl rosters and media depth charts show each team's starting lineup hasn't changed in decades. Every team is still shown with two receivers, a fullback and a running back, the formation that became standard thanks to the development of the I-formation.

The I-formation has been the dominant offensive formation in the NFL and has stayed effective for decades because of the way it balances the running and passing attack. We'll get into just how that balance is achieved, but first a little bit of history.

Origins

To cap the 1940 season, Chicago Bears coach George Halas used the T-formation (with the fullback directly behind the quarterback and the two halfbacks on either side of the fullback) to beat the Redskins 73-0 in the NFL championship game. Before long other teams saw that the T was more versatile than its predecessor, the single wing, and they adopted the T for themselves. By 1952, the Steelers (the last holdouts) switched to the T, and the single wing was out of pro football.

But around the same time, Tom Nugent, the football coach at Virginia Military Institute, had a new idea. Instead of having halfbacks on each side of the fullback, he thought it made more sense to line up the halfbacks behind the fullback. With the offensive backfield in a straight line, they looked more like an 'I' than a 'T', and a new formation was named.

After five years at VMI, Nugent brought the I to Florida State in 1954, and it began to spread, most notably to John McKay, who used the formation to win the national championship at USC in 1962. Before long, NFL teams took notice, and the I became the most common set in pro football.

Coaches who frequently run the I-formation often extol its virtues with statements like, "We just want to line up and come right at 'em." But there's nothing inherently tougher about the I than there is about any other formation. What set the I apart from the T and many of the other formations of the early days of football is that it lent itself to a versatile offensive attack. That versatility is still valuable in the modern game.

The Playbook

A typical bread-and-butter play from the I-formation might have a name like "I right 32 iso". That means an I formation with the right side being the strong side -- the tight end and the flanker (the wide receiver a yard behind the line of scrimmage) are lined up to the right, with a split end (the wide receiver on the line of scrimmage) on the left. The 32 means the halfback (or the 3-back) is getting the ball and running through the 2-hole (between the center and right guard). "Iso" is short for isolation, meaning the fullback is leading the running back through the hole and engaging the middle linebacker in an isolation, one-on-one block. (You know, the kind of block where the TV audience hears Ray Lewis complain that he was double-teamed.)

The offensive linemen block the players in front of them, with each tackle taking a defensive end, a guard blocking one defensive tackle alone and the other guard and the center double-teaming the other defensive tackle. The tight end blocks the strongside linebacker, and the two receivers might run a flag or a hook route to take the cornerbacks out of the play.

A play like I right 32 iso won't produce a lot of long runs, but that's not what it's designed for. If the right personnel executes it properly, it will accomplish one of two things: Either it will consistently allow the offense to gain four yards a pop (and an offense that can do that will march right down the field) or it will force the defense to bring the strong safety close to the line of scrimmage for run support. When TV announcers describe this, they call it "eight in the box, " and it means the defense is susceptible to the other bread-and-butter play of the I-formation: the play-action pass.

When the offense sees the strong safety playing run, it becomes clear that it's time to run the play action. The linemen and fullback have the same blocking responsibilities and try to make it look like a running play. The quarterback fakes a handoff to the running back, but instead of giving up the ball he goes into his seven-step drop. With the strong safety playing run support, the cornerback has no help in coverage on the flanker, who becomes the primary receiver on the play.

Let's talk a little more about the fullback, who usually lines up about four yards behind the quarterback, with the running back usually about three yards further behind. At seven yards behind the line of scrimmage, the running back can easily survey the field to see where the defensive players are lining up, and he can get a full head of steam so that he's at full speed when he hits the line of scrimmage. The running back also has time to watch blocks develop and can find cutback lanes.

The flipside, of course, is that a handoff to the running back in the I takes longer to develop than a handoff to the fullback, and that gives the defense more time to react. That's why in the early days of the I-formation, the fullback regularly carried the ball, especially in short-yardage situations. Today, however, football is a much more specialized game, and I-formation fullbacks are blockers almost exclusively and rarely carry the ball.

Which Fullbacks do it Best?

But even though he doesn't run much anymore, the fullback is still one of the most important pieces of the I-formation. If he isn't able to effectively use that isolation block on the middle linebacker, the play won't work.

The best game I've ever seen by a blocking fullback was Cory Schlesinger's performance against the Bears on October 20, 2002. The Lions had 39 runs for 192 yards, and nearly all of them were on I-formation runs with Cory Schlesinger providing the lead block on Brian Urlacher (James Stewart got most of the carries). When a fullback dominates a middle linebacker as completely as Schlesinger dominated Urlacher that day, an I-formation offense is nearly impossible to stop.

Unfortunately, football statistics -- even the most sophisticated ones like those we use at Football Outsiders -- are greatly lacking in their assessment of which fullbacks do the best job of providing lead blocks for their running backs. About the best thing we can do is examine each running back's I-formation splits and infer what those splits tell us about the fullbacks who block for them. Stats Inc. keeps track of how running backs do in the I-formation, although they don't tell you the context of those carries.

Here are the leaders in a number of I-formation categories, starting with total carries:

Even though the Texans use the three-receiver set as their base offense -- Andre Johnson, Corey Bradford, and Jabar Gaffney are all starters -- Norris is the prototypical I-formation fullback. Last year he had one carry and four receptions, which sounds like no contribution at all until you realize how often the Texans counted on the 254-pounder to lead their running game.

Warrick Dunn's 126 carries in the I-formation were a lot, especially when you consider that T.J. Duckett had another 67. But when we look at the top running backs in terms of their yards per attempt in the I-formation, we see some interesting things, especially about the Falcons:

Duckett was No. 1 in the league in yards per attempt in the I, and it's striking to compare the numbers of Dunn and Duckett when they're in the I and when they're not in the I. Duckett averages 5.5 yards a carry in the I and 3.8 yards a carry when he's not in the I. Dunn averages 4.3 yards a carry in the I and 4.1 yards a carry when he's not in the I. That demonstrates that Duckett thrives when he's running straight ahead into a pile, but is less effective when there's more open space around the backfield. Duckett never once got stuffed for no gain or a loss on his 67 carries in the I-formation.

Two of the top five running backs in yards per carry are Broncos running behind Patrick Hape or Kyle Johnson. For some odd reason Hape is listed as a tight end, and the TV announcers dutifully call him a tight end, but when you watch the Broncos you see that he actually plays fullback. He clearly does a good job of it, although if you don't already know that the Broncos do a good job of run blocking, this probably isn't the right website for you.

Next let's look at touchdowns in the I-formation:

Priest Holmes only took a handoff in the I-formation 75 times in his injury-shortened 2004 season, and yet he scored 14 times. Obviously, the Chiefs love using the I in goal-line situations, and Tony Richardson does a great job of leading Holmes and his backups into the end zone. On the opposite end, Marshall Faulk had 74 carries in the I and didn't score on any of them. Mike Martz generally doesn't like the I in goal-line situations, subscribing to the theory that it's better to spread out opposing defenses with an extra receiver in the red zone than to have them all crowding the middle of the field when a fullback is in.

Because the point of plays like I right 32 iso is to get four yards when the team needs four yards, if I had to choose one statistic to use to judge a fullback's effectiveness, it would be the percent of plays on which his running back got a first down from the I-formation. So let's look at that:

Sowell and Richardson have made plenty of All Pro teams, so it's no surprise to see them on the top of the list. Perhaps Zach Crockett, James Mungro, and Mike Karney deserve more credit for the roles they play.

Wrapping it Up

The I-formation has been the dominant offensive formation of the post-merger era, but it's far from universal. Don Coryell had success with the I early in his coaching career but later moved away from it with his high-scoring San Diego Chargers teams. Joe Gibbs, who played in college for Coryell at San Diego State, followed his mentor's lead and eschewed the fullback for an H-back who was more a threat as a receiver but not as useful as a straight-ahead blocker. Last year, Gibbs' Redskins rarely ran out of the I, and two of the other teams that most scrupulously avoided the I were run by Gibbs disciples: The Panthers with Dan Henning as offensive coordinator and the Vikings with Mike Tice as head coach and Scott Linehan as offensive coordinator. Most teams, even teams that prefer single-back sets like the Colts, still keep a full slate of I-formation plays in the playbook.

Although the offensive innovators (and the rule-makers) have made the NFL a more pass-happy league in recent years, the I isn't going anywhere. Fullbacks of today aren't as important to their teams as they were 30 years ago, but when a team needs a couple of yards, there's no better way to get them than having a lead-blocking fullback isolated on the middle linebacker.