Welcome to one of the most rapid periods of tactical evolution in NFL history! It's an exciting time when old strategies are being rethought while new ones are tested, a time when everything from play-calling procedures to roster development is being revised and reimagined. 

For those of us who slogged through the 1990s, when every offense was a West Coast system desperately seeking a Joe Montana clone and defenses came in two flavors, this new era of read options, frantic sideline signaling, and anything-goes defense is truly thrilling. No two teams do things precisely the same way anymore. Some tactical wrinkles will become forgotten fads (think: Wildcat), others will encode themselves on the league's strategic DNA, and we won't know which is which until they succeed or fail on the field. 

What follows is an inside-the-numbers look at just how quickly new trends and rules are reshaping the NFL. This is not your father's football league anymore. Things are happening so quickly that it soon will not even be your big brother's, either. 

Offenses are Getting Faster

Chip Kelly got the jump on the NFL in his rookie coaching season. His innovative Eagles offense finished second to the Broncos in total yards (6,676, or 417 yards per game) and tied with the Broncos in yards per play (6.3). While Kelly's read-option offense got most of the attention at the college level, his up-tempo, no-huddle scheme proved far more dangerous in the NFL. The Eagles lined up without a huddle on 68 percent of their offensive plays, often leaving defenders disorganized and sucking wind.

Kelly is a true trendsetter, but NFL offenses were accelerating for several years before he arrived. Researcher Jim Armstrong has tracked offensive pace for years, measuring the average time a team takes to snap the football and adjusting for factors like the two-minute offense and other hurry-up (or slow down) situations. As Table One shows, the average team snaps the football more than a second faster now than it did four years ago.

Season Average Seconds/Play Fastest Seconds/Play Fastest Team
2013 29.79 23.88 Eagles
2012 30.19 24.53 Patriots
2011 30.45 26.43 Patriots
2010 30.84 28.36 Colts

 

Kelly was the fastest and most furious up-tempo advocate in the NFL last year, but he was not alone: The Bills, coached by fellow first-year collegiate innovator Doug Marrone, finished second in situation-adjusted offensive pace at 24.92 seconds per snap. Kelly and Marrone were followed by the Broncos and Patriots, and the table shows that Tom Brady and Peyton Manning have been conducting a hurry-up arms race for years. Next-gen college coaches like Marrone and Kelly are taking high-speed tactics out of the Brady-Manning realm and bringing them to the masses. 

Not every team is ready to go no-huddle two-thirds of the time, and most teams are using the hurry-up the way a crafty baseball pitcher changes speeds. Sometimes the defense can huddle and substitute, sometimes it cannot, but it can never get comfortable. As for Kelly, he thinks the Eagles can go even faster. Do not doubt him.

Defense is Getting More Diverse

You are probably aware that the 3-4 and 4-3 designations for defenses are woefully out of date. From edge rushers who are neither end nor linebacker to nickel cornerbacks who play more snaps than the starters, defensive strategies have evolved beyond these decades-old labels.

But you may not realize how acute the problem is. Football Outsiders tracks the number of linemen, linebackers, and defensive backs on the field for every snap, using team sources to assign positions for versatile players. Here are the percentages for the most common personnel groups, with goal line situations (and their 6-4-1 formations) eliminated:

Personnel (DL-LB-DB) Percent of Snaps
4-2-5 27.9%
4-3-4 18.9%
3-4-4 17.7%
2-4-5 8.2%
6 DBs 8.2%
3-3-4 7.5%
Other 11.6%

 

The "other" category contains eight defensive backs at Hail Mary time, six linemen on fourth-and-inches, and other situational wrinkles. As you can see, the base defense in the NFL is a nickel defense. Five or more defensive backs are on the field for 51.8 percent of snaps. A typical team will be in its "base" 3-4 or 4-3 for less than one play out of every five.

The surprise entry in Table Two is the 2-4-5 defense. The Chiefs used the 2-4-5 or 2-3-6 on 45 percent of defensive plays last season, essentially making Bob Sutton's base formation a two-lineman set. Dom Capers' Packers used just two down linemen 64 percent of the time. These teams may still list three defensive line starters on their depth charts, but new and old coordinators are increasingly limited by only their personnel, daring, and imaginations. 

Injuries are a Bigger Problem 

If you think your favorite team had its hardest-luck injury season ever in 2013, you may be right, and you are certainly not alone. Football Outsiders tracks injuries using the Adjusted Games Lost method, which compresses a year's worth of injury reports into a scale determining how many games a team's key players missed during the year. As Table Three shows, games lost to injury have risen steadily over four years:

Year AGL Per Team
2010 50.9
2011 60.0
2012 64.5
2013 70.2

 

Think of 70.2 AGL as four starters lost for the season, plus a fifth starter missing six full games (16 X 4 + 6 = 70). That was an average team's injury lode in 2013. Just four years ago, the average team suffered the equivalent of three lost starters, plus a fourth starter for three games. That's the equivalent of one additional season-ending injury per team!

You may interpret this data as evidence that the NFL's safety protocols are not working. In fact, it may be proof that they are working: Players are taking much more time off after concussions and other high-risk injuries than they did in past years. 

From a strategic standpoint, the injury data tells us that depth is more important than ever. A team that is not ready to replace four or five starters cannot expect to make it to the playoffs. Teams are adjusting everything from player workloads to salary cap allocations to adapt to the new reality.

Going-for-It is Getting Popular

Coaches are beginning to look at their huge, mobile quarterbacks and intricate, option-heavy playbooks and wondering why they are settling for field goals on fourth and goal. The 2013 season saw a sharp upturn in the number of fourth-and-goal conversion attempts, as Table Four. Fourth quarter situations were removed, as a coach's hand is obviously forced in many late-game situations:

Year Attempts Conversions
2010 17 7
2011 11 4
2012 18 12
2013 30 14

 

Twenty-one different teams attempted a fourth-and-goal conversion before the fourth quarter in 2013, and the attempts came in a variety of circumstances: opening drive, up by a touchdown, even down by three points. 

The low conversion rate in 2013 may dissuade coaches from being daring in the future, but it might not: Even a failed fourth-and-goal from the one-yard line brings the promise of a pinned opponent and excellent field position. The Seahawks attempted a fourth-and-goal conversion in the NFC Championship Game against the 49ers, for example. Russell Wilson fumbled, but the Seahawks got the ball back with excellent field position just two plays later, setting up the field goal that put the game out of reach.

Why should a team with Wilson, Marshawn Lynch, and a vicious defense settle for a field goal at the one-yard line? Now that the Seahawks answered that question on the way to the Super Bowl, look for the copycats to continue asking it.