The history of offense in the NFL is not a linear one. The early ’70s was the dead-ball era of the passing game, and it’s largely true that pass frequency and efficiency have steadily increased since then. But NFL teams passed more frequently in the ’60s than they did in the ’70s, and passing ratios wildly fluctuated in the ’50s. The picture below shows the league-average pass ratio for the NFL ^[1]I have excluded the AFL statistics from this data set. for each year from 1950 to 1980. Pass ratio is simply defined as (Pass Attempts + Sacks) / (Pass Attempts + Sacks + Rush Attempts).

As you can see, 1956 represents a huge outlier over the 30-year period. Pass ratios dropped significantly in 1956, increased slightly in 1957, and then spiked back up, seemingly without reason. The other main valley, of course, was in the mid-1970s. The pass-to-run ratio dropped every year after the merger before plummeting to 43% in ’73. It spiked back up temporarily in ’74 and ’75 before dropping again, bottoming out at 42% in ’77 and necessitating the 1978 rules changes.

The next graph shows the league-average ANY/A for each season (in green) and the Adjusted Yards per Carry average (Rushing Yards + 20*Rushing TDs) / (Rush Attempts) in red. As you can see, passing was slightly more effective than rushing in the mid-’60s, which presumably caused a shift towards more passing. As pass efficiency decreased, so did pass attempts.

From 1950 to 1953, teams averaged roughly 3.25 ANY/A, and at least based on the efficiency numbers, they did not run as often as they should have. Teams passed on 49% of all plays in ’53 and ’54 and on 47% of all plays in 1958. But in the three intervening years, the forward pass nearly evaporated, with the nadir coming in 1956 (39.3%).

It’s hard to explain what caused the shift. After all, teams averaged 3.9 Adjusted Net Yards per Attempt from ’54 to ’57, so it seems odd that teams essentially gave up passing without a concomitant justification. It’s possible that the shift was in response to the low-efficiency numbers earlier in the decade, and the return to the more balanced approach later in the decade only occurred once pass efficiency numbers improved.  To investigate, I looked at the pass/run ratios and gross umber of pass attempts for each team in 1954, 1956, and 1958, to get a sense of which teams were causing the big shift in the middle.

Three teams made most drastic changes in pass/run ratio, but no team shifted philosophies quite like the Bears. In 1954 the team had George Blanda and Zeke Bratkowski and a pair of young receivers in Harlon Hill and Jim Dooley. Despite an 8-4 record the ’54 Bears led the NFL in pass attempts. In 1955 Rick Casares joined Chicago and Ed Brown took over at quarterback, ushering in a run-first era. In 1956 the Bears ran on nearly two-thirds of their plays; when they didn’t run, Brown would throw it deep to Hill, who caught 47 passes for 1,128 yards and 11 TDs in 12 games, the 13th most dominant season by any wide receiver.

The Eagles and Cardinals also underwent significant change. The ’54 Eagles were relatively pass-happy with Adrian Burk and Bobby Thomason at quarterback and a 31-year-old Pete Pihos. The next year the Eagles led the NFL with 400 pass attempts (excluding sacks), but that number dropped to just 249 the following season. What happened? For starters, a coaching change that seemed to usher in a more run-happy environment. And with Pihos retired and #2 WR Bill Stribling injured, the quarterbacks really struggled in 1956, as Thomason and Burk threw just 5 touchdowns against 27 interceptions (they threw 52 TDs and 53 INTs in ’54 and ’55).

Meanwhile, the other team in Chicago, the Cardinals, also re-emphasized the run. The Cardinals were a bad team in ’54 and future Packer Lamar McHan threw 6 TDs against 22 interceptions. But by ’56, McHan was playing better and Ollie Matson and Johnny Olszewski gave the team a strong rushing attack. The Cardinals ranked 2nd in points allowed and rush attempts, and finished with a 7-5 record, so I think their shift in philosophy was an offshoot of the team improving. The retirement of Otto Graham in Cleveland and the benching of Norm Van Brocklin in Los Angeles didn’t help the passing environment, either.

Of course, looking at offense tells only half of the story. The transformation occurring on the other side of the ball was perhaps more significant. In the early ’50s, most teams played a 5-2 defense. Players like Bill Willis in Cleveland, Les Bingaman in Detroit, Bucko Kilroy with the Eagles and the Rams’ Stan West were among the best defenders of their day — and all played a position known as middle guard, a nose tackle/middle linebacker hybrid. But the 4-3 umbrella defense came of age in the mid-’50s, and it seems logical to assume that teams thought it would be easier to run against four-man lines. In particular, I think 1956 was the first year that the 4-3 defense became a staple in the NFL. But once teams realized that it was not any easier to run against this defense, offenses appeared to have decided to go back to the more balanced approach. That would also explain why the 1956 season was so run heavy.

Another possible explanation is that even back then, the NFL was a copycat league. The 1955 NFL champion was Cleveland, who finished 1st in rush attempts and last in pass attempts. Those ranks are Game Script-aided, of course, but I’m not sure that NFL coaches in 1956 were experts in advanced statistical analysis.

There’s no right answer, of course. I think all of these factors played a part — the decline in the quality of quarterback play, the invention of the umbrella defense, an influx of young running talent, and a realization that rushing was more effective probably all played a part. As a result, 1956 stands out on an island as one of the most unique seasons in NFL history.