In Era of Explosive Offenses, What Does the Future Hold for NFL Defenses?

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In Era of Explosive Offenses, What Does the Future Hold for NFL Defenses?
Christian Petersen/Getty Images

It's an inescapable law of football physics: defense always wins.

Since the dawn of football history, defenses have had the advantage over offenses. Even when new players, new coaches or new rules have breathed life into the offensive game, it's only been a matter of time before the suffocating blanket of defense has snuffed it back out.

In today's game, though, offense is blowing up like never before. The combination of rules changes, the prevalence of the shotgun formation and the switch to endless multiple sets have defenses dropping back in soft zones and hoping they hang on.

Have today's wildly multiple formations, unprecedented pass-to-run ratios and read-option shenanigans finally broken the cycle?

Can defenses ever regain the permanent edge they seem to have lost?

 

The Karmic Cycle of Football

On the surface, it seems like the offense has the upper hand. They start with the ball, after all, and only they know how they plan to advance it. Offense is active; defense is reactive. Defense will always be scrambling to adjust to whatever the offense plans to do...right?

Wrong.

Go find a 30-foot tape measure and pace off 10 yards. It's not that far.

But offenses still get four tries to push through defenses that short little way and often can't. Defense is a wall to be broken through, a force to be reckoned with. Offenses can sometimes force the defense to adjust, but more often, defenses are the ones attacking, disrupting and dictating.

Every big football fan knows the phrase "we'll take what the defense gives us," but has any defensive player or coach ever said the reverse?

What we call football, in its original state, was a profoundly low-scoring game. It was a brutal affair, trench warfare slowly grinding back and forth along the gridiron. Field goals were rare, and touchdowns even rarer.

It started as a variant of association football—"soccer," for short—and rugby. The Official Playing Rules and Casebook of the NFL is still filled with terms from both sports (going out of bounds is still officially called putting the ball "in touch," for example). Football was brutal like rugby and low scoring like soccer.

In all of the 1920s, NFL teams averaged 10 points or more per game only once, in 1924.

The incorporation of the forward pass—and many other rule changes—dramatically increased both offensive production and scoring overall. Over 90 years, the battle between offense and defense has raged, but every time offenses gain the advantage, defenses take it back.

For all of today's fancy schemes and high-priced talent, NFL offenses can still play an hour of football without scoring a single point—just ask Eli Manning and the New York Giants.

Let's look at how league-wide scoring averages have risen and fallen since 1932, the first year the NFL kept official statistics. We'll also look at average first downs per game since 1936, the first year that was tracked. As with most of the numbers in this piece, you can thank Pro Football Reference for them:

As you can see, scoring climbed like a rocket from the single-digit days of the 1920s until 1948, which is still the highest-scoring season in NFL history. The league-wide per-team scoring average hit 23.2 points per game, but then trended downward.

It reached a low of 19.8 in 1957 before bouncing back up toward the second-highest-scoring season in NFL history, 1965 (23.1 average). Then another steep decline, this one leading to the lowest-scoring season in modern NFL history, 1977.

As discussed in this article's companion piece, 1978 saw the introduction of several rule changes specifically designed to open up the passing game and increase scoring. They worked; scoring immediately made a huge jump and, save for a three-year recession in the early 1990s, has been increasing ever since.

After the rules of the game stabilized in the postwar era (that 1948 season was the first one where all officials used whistles instead of horns!), there was an ongoing cycle of offensive innovation and defensive domination.

We see the red line in that chart (a four-year moving average) rolling like a sine wave: a peak in 1948, a trough in 1958, a peak in the late 1960s, a trough in 1977, a peak in the mid-1980s, a trough in the early 1990s.

Every rule change or systematic innovation that boosted offensive production was eventually adapted to, every rise in scoring eventually repressed. Defense has always been an irresistible, entropic force dragging offenses back down to their rugby-scrum ancestry...until now.

What's happening?

 

Moving the Chains

We know the tripling of average scoring rates from the 1920s to the 1940s happened because of the development of the forward pass. Innovations like the center-to-quarterback snap and the Chicago Bears' "T" offense were evolutionary leaps, but they came with growing pains. 

Though offenses were putting up big points with the passing game, they were also turning it over and getting sacked like crazy. NFL coaches still viewed trench warfare as the heart of the game and running the ball the best, safest way to progress down the field.

Let's look at that points chart again, but this time with the average number of first downs achieved by each team, each game laid on in green:

At first blush, the trends in first downs follow the points trends. Look a little more closely at the four-year moving averages, which are in red and black. The straight linear climb of scoring from the 1920s up until 1950 or so is not at all mirrored by first downs.

NFL teams averaged 8.8 first downs a game in 1935, then jumped up to 10.8 in 1936 and held steady around 11 for nine years. Then, in 1945, they averaged 12.1 first downs a game. In 1946, 14.8. In 1947, 16.6.

Offenses were suddenly sustaining drives much longer, moving the ball through defenses much more easily. Of course, this coincided with a dramatic increase in passing frequency and effectiveness:

In this chart, I've included the 1942-1948 passing numbers and each data point. Look how remarkably flat all the passing numbers are until 1946. There's a massive jump in average first downs per game, from 12.1 per team to 14.8—a 10.7 percent boost. Interestingly, though, passing first downs only went up by an average of 1.0 that season.

For the first time, NFL defenses were having to focus on stopping the pass at the expense of the run defense. In 1947, offenses figured that out.

NFL teams attempted an average of 24.9 passes per game in 1947, up 16.9 percent from 1946. With the increase in attempts, they completed an average of 2.2 more passes per game for 1.4 more aerial first downs.

Again, that bore dividends in the run game: Teams averaged 16.6 total first downs per game in 1947, up 12.2 percent from the year before and 37.2 percent from 1945.

Overall, from 1945 to 1948, pass attempts went up 18.9 percent, completions 30 percent, first downs 43.8 percent and passing first downs 56.3 percent.

Let's put that in perspective. If an offensive explosion like the 1945-1948 one occurred today, the 20.0 first downs per game teams are averaging now would become 28.9 first downs per game by 2016.

The weird thing is, once this explosion occurred, it stayed remarkably flat. Though scoring had ramped up much earlier, first downs rose only slightly until the three-year explosion. Bizarrely, first downs stayed flat as a tabletop from 1948 until about 1975—that's 27 years! Meanwhile, scoring was fluctuating all over the place.

We see something crazy in 1977: a precipitous drop in point scoring, so low it nearly reached parity with first downs (17.2). Then came the 1978 rules changes. Since then, first downs have moved in tandem with scoring, give or take, until today.

What's going on here?

Let's look at the points and first downs per game chart one more time. This time, the gap between them is highlighted in vertical orange bars and the difference is charted in orange at the bottom:

That gap represents the difference between offensive effectiveness—how easily offenses are moving the ball—and scoring. When the gap is wide, there are more points coming out of big plays; defenses aren't bending, but they are breaking. When it's narrow, defenses aren't breaking.

The differential reached its peak in 1943, when teams were averaging 19.5 points per game, but only 11.7 first downs. Think about an offense scoring on at least three drives, but only moving the sticks 11 times in a game. That's what the average NFL offense looked like in 1943.

In the offensive study, I compared the careers of the Detroit Lions' Matthew Stafford and legendary Raiders quarterback Daryle Lamonica. Lamonica put up most of his numbers from 1967 through 1972, when the differential between points and first downs was nearly twice what it is today.

No wonder Stafford will nearly match Lamonica's yardage total this season, but won't match his touchdown total until at least 2015.

By 1977, it was the reverse: offenses were converting an average of 16.9 first downs per game, but scoring only 17.2 points. Defenses weren't bending or breaking.

 

The Rise of Specialization

So, what happened in the late 1940s that put the brakes on the stunning increase in offensive first downs? What happened in the late 1970s that reduced scoring to pre-World War II levels without really slowing offenses down?

The short answer is "defense won."

In the late 1940s, passing, first downs and scoring reached an equilibrium because offenses were running out of time. If we look at the companion piece, offenses in 1948 were getting off an average of 68.2 plays per game, a breakneck pace on par with today's fastest hurry-up offenses.

In 1950, per NFL.com, the league permanently adopted unlimited substitutions. This cleared the way for full-time two-platoon football, allowing not only for positional specialization, but keeping players on both sides of the ball much fresher.

The result was an immediate decline in offensive plays, yards and scoring. Instead of exhausted ironmen getting beaten deep, specialized defensive linemen played better against the run and pass, and specialized secondaries improved their coverage.

David Maxwell/Getty Images
Hall of Famer Deacon Jones was the prototypical pass-rushing defensive end.

Despite offensive innovators like Vince Lombardi driving a scoring mini-boom in the early 1960s, the overall trend from 1950 to 1977 is a long decline in scoring and a first-down flatline. By 1977, snarling, nasty secondaries and huge, fast defensive linemen had all but eliminated the big play from the game.

This is what is often called football's "dead ball era," and with good reason.

In the late 1960s, rushing and passing play-calling had nearly reached parity. In 1966, offenses maintained an average 51.6 percent run to 48.4 percent pass ratio. The defensive clampdown turned coaches away from the pass again, though. In 1977, that ratio had widened back out to 59.9 percent run, 40.1 percent pass—a ratio not seen for 20 years.

 

The Modern Era

As discussed in the other piece, the 1978 rules changes put offenses back on the fast track. Passing went up dramatically, as did passing effectiveness. In 1982, offenses called more passes than runs for the first time in NFL history. After 1983, they never looked back, calling passes ever more often. In 2013 so far, offenses are calling 58.4 percent passes and just 41.6 percent runs.

One of the most interesting periods in the history of NFL defense, though, was the early 1990s. After the explosive offenses of Don "Air" Coryell's San Diego Chargers and devastatingly effective offenses of Bill Walsh's San Francisco 49ers introduced an era of widespread passing and much higher scoring, there was another offensive "recession."

Scoring, first downs and the "big play" gap between them all dwindled. In fact, 1993's differential between average first downs and points per game was a mere 0.6, straight out of the dead ball era!

What sparked this was the reversal of the 1970s and 1980s trend toward blitzing 3-4 defenses and pass-rushing linebackers.

The rise of modern pass-protecting left tackles like Anthony Munoz helped neutralize outside linebackers not named Lawrence Taylor. The rise of the first full-time three- and four-wide receiver offenses (like the Run N' Shoot, used by the Houston Oilers, Detroit Lions and Atlanta Falcons) in the late 1980s forced defenses to get more pass rush from their defensive line.

Pass rush began to come from the interior, from defensive tackles like John Randle and Cortez Kennedy, as well as defensive ends like Reggie White.

Fritz Shurmur, a longtime defensive coordinator who spent much of the 1980s with the then-Los Angeles Rams and the early 1990s with the then-Phoenix Cardinals, developed the "Big Nickel" defense, according to Jene Bramel of the New York Times' Fifth Down Blog.

This 4-2-5 alignment allowed defenses of the early 1990s to cover newfangled slot receivers and pass-catching running backs while still getting pressure from their big front four. Throughout much of the 2000s, the 4-2-5 became the dominant passing-down alignment.

As Bramel wrote, by 1980, three-quarters of the NFL used a 3-4 front, but by the mid-1990s, that trend had almost completely reversed. Today, most defenses use five (or more!) defensive backs more often than not, regardless of down.

Spread offenses being defended by extra defensive backs, getting pass rush with minimal pass-rushers, abandoning run defense because offenses are abandoning the run...sound familiar? It's exactly what defenses are doing now to stop today's spread offenses—except in the early 1990s, it worked.

 

Is the Cycle Broken?

This is the billion-dollar question: have today's spread offenses, with their shotgun snaps, four- and five-receiver sets, multi-faceted running backs, vertical-threat tight ends, athletic offensive lines and zone-read run schemes become impossible to defend?

Has offense gotten so powerful that defenses must simply drop back in a shapeless "amoeba" zone defense and hope the quarterback makes a mistake?

It's hard to deny the trends. Throughout NFL history, the "wavelength" of scoring trends—of offenses making advances and defenses adapting—has gotten shorter and shorter, the cat-and-mouse game getting faster and faster.

Since the days of Reggie White and nickel defenses, offenses have gone back to classical running and play-action passing, then on to extreme shotgun-based spreads, and defenses have gone from 4-3 alignments back to zone blitz 3-4s, and now multiple/hybrid alignments galore.

Patrick Smith/Getty Images

Offensive production, though, has only increased. Yardage and scoring have only increased. Passing has only increased. Philadelphia Eagles head coach Chip Kelly may be ushering in a new era of zone-read rushing, but that only changes the method of scoring; the Eagles put up points as fast as anyone.

The nature of trench-warfare football has always favored the defense, but it's time to admit the fundamental nature of the game has changed. It no longer "all starts with the offensive line." It's no longer a physical battle over the line of scrimmage. Line play is slowly vanishing from the game, Kelly's offense and its derivatives notwithstanding.

Given the NFL's always pushed for more fan-friendly scoring and fan-friendly safety, they may finally be getting the "flag football" league they've always wanted.

Now, it's on defensive coordinators to adjust, improve and adapt as they always have—or the NFL to, for the first time ever, consider changing the rules to favor the defense.

Don't hold your breath.

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