You remember 1976, don’t you? Two teams — the Colts with Bert Jones and Roger Carr, and the Raiders with Ken Stabler and Cliff Branch — stood out from the pack when it came to pass efficiency that season. The Colts led the NFL in passing yards, ranked 2nd in passing touchdowns, and threw just 10 interceptions, tied for the fewest in the NFL. Oakland threw 33 touchdown passes — nine more than the Colts and 12 more than any other team in football — while ranking 3rd in passing yards. Both teams averaged 7.5 Net Yards per Pass Attempt, while every other team was below seven in that metric. Those two teams went a combined 24-4.
The next four best passing teams were St. Louis, Dallas, Minnesota and Los Angeles. Each of those teams went 10-4 or better. In fact, the linear relationship between pass efficiency and team record was quite strong that year. Take a look at the chart below, which plots Relative ANY/A — i.e., Adjusted Net Yards per Attempt relative to league average — on the X-Axis, and Winning Percentage on the Y-Axis:
This shows an incredibly tight relationship between just one metric — Adjusted Net Yards per Attempt — and team success. Now, let’s run those same numbers for the 2014 season. And, to compare apples to apples, let’s use the same dimensions, with the X-Axis running from a RANY/A of -4.0 to 4.0, and the Y-Axis from 0 to 1:
Pictures can tell a 1,000 words, and one look here is a great representation of how the spread of both passing efficiency (and, to a less extent, winning) is more compressed now than it was in 1976. But what’s interesting is that the correlation coefficient between pass efficiency and winning was the same in both years: 0.75. In other words, pass efficiency was about as responsible for team success in 1976 as it was in 2014.
For 2014, the best-fit formula to predict winning percentage was 0.50 + 0.147*RANY/A. For 1976, it was 0.50 + 0.113 *RANY/A. This means it “costs” less RANY/A to gain wins in 2014, but since it’s harder to get RANY/A — because pass efficiency is more compressed — it winds up canceling out. In other words, while it takes less RANY/A or ANY/A to gain wins, it also costs more to “buy” pass efficiency now.
Now, how about 1953?
Here, the CC was 0.82, which means pass efficiency was even more importan to team success in 1953 than it was in ’76 or ’14. The best-fit formula for ’53 to predict winning percentage was 0.49+ 0.094 * RANY/A. Again, we see that in this era, you had to buy more RANY/A to get wins, but it was also relatively cheap to buy RANY/A — you would never see a team with a RANY/A of +5.0 today the way we did with the ’53 Browns.
1953 was somewhat of an outlier year: the decade of the ’50s was not like that. The graph below shows the correlation coefficient between RANY/A and team winning percentage for each year from 1950 to 2014. The blue line represents the NFL, the red line displays the AFL.
This is just the first step in trying to answer the question of how much does passing matter now versus at various points in NFL history. That’s enough for one day, but before we move to Part II, I need some help. What sort of queries would you be interested in seeing? How would you go about answering the question of how much passing “matters” — whatever that means — now versus in 1976?