FNQB: Are Changes in NYPA a Strong Measure of the Strength of Passing Environments?
Not to possibly curb your desire to read the rest of this article, but the answer to the headline question is “not as strongly as I had hoped.” The reasoning behind such a conclusion is that my methodology involved using only the passing performances that qualified at a value between 99 and 101 on the pro-football-reference passing index for net yards per attempt, and the result of the research was ultimately a sample size issue. NYPA is well known as a solid predictive measure of quarterback/offensive aptitude, and so by taking players who were almost perfectly average in this measure between 1970 and 2010, I wanted to see if we could get a good context for the strength of passing in the NFL over the last 40 years. Still, I have plenty of interesting observations to offer.
The main problem is sample size earlier than 1970. I had roughly assumed that in any given season, one out of the 25ish passers who threw a majority of their teams passes would end up roughly at league average in YPA. The accuracy of my methodology makes it back to roughly 1977. This is a bit problematic, because the passing environment very famously loosened in 1978 with the enactment of the “Mel Blount rules” for cornerbacks, rules that were reemphasized in 2004 in a movement lead by the Colts. Obviously, I’d like a better sample from 1977 and before, but the “perfectly average in NYPA” method skimps here.
What we can tell about the pre-Blount rules era is best captured by completion percentage, a value that hardly ever exceeded 53% amongst league average passers in the mid seventies. Although the baseline today is now around 62%, exceeding 60% in the sixties and seventies meant your name was “Tarkenton,” or “Jurgensen,” or “Anderson.” Passers who, in a couple of words, were clearly ahead of their time. After 1975, that began to relax a little bit, and great teams started to have high efficiency offenses, so you’ll see guys like Terry Bradshaw and Ken Stabler with some excellent seasons in the seventies.
If we move our focus to a 16 game NFL season beginning in 1978 with relaxed passing rules, it’s just not clear that the average QB season has resulted in more recent names doing the most to throw their teams to victory. Take a look at the list of average NYPA seasons re-sorted by yards per attempt efficiency. David Garrard last season ranks no. 1: the best yards per attempt in the last forty years by a player with an average season. He is followed by a number of players from the mid eighties: a couple of Neil Lomax seasons, a Warren Moon year, and a Ron Jaworski season. Then we end up in the middle of this decade. Anyway, sorting by yards per attempt puts the results all over the map, and doesn’t really do anything to define an era. The variability of sacks by player doesn’t fall neatly along era lines. And that is why sorting by yards/attempt efficiency doesn’t work.
Actually, this is where passer rating can really help. Here is the same list sorted by passer rating, a metric that doesn’t involve sack rate in any way, but does a good job capturing the increases in the efficiency of NFL passing games thanks to declining interception rates. One of the main observations of this project is that, since 2007, it’s quite common for a player with an average showing in NYPA to put up an 80.0 or better in quarterback rating. Prior to 2007, it was relatively uncommon for a player’s QB rating to exceed 80 if his NYPA was average. Since then, it’s happened 10 times.
Rating also shows us that, while there was a measurable late seventies bump in passing offense, it was short lived. Passing totals REALLY opened up in the mid-eighties, and the truth is (as YPA shows above), NFL defenses were vastly behind for a period of four or five years. There was probably no larger offense-defense discrepancy (at least in favor of offense) than in the mid-eighties when the Chicago Bears could stop anyone they wanted and every other team could score. QB rating shows us that from 1983 though 1988, the average QB season came in steadily above the 75.0 passer rating line for the first time with the average QB completing about 58% of his passes. Those numbers look light today, but defenses are actually a bit better at preventing yards now than they were in the eighties. It was not at all uncommon to average over 200 passing yards per game for the entire season.
I don’t really know why offensive passing numbers stagnated in the early nineties. If I had to venture a guess, I would suggest that the offensive-defensive discrepancy seen in the mid-eighties closed, perhaps of factors and adjustments that we would suggest to be rather normal. I do know that 1994 was an aberration year because a bunch of hall of fame quarterbacks had career years, pushing the average passing year towards the levels we currently see in the NFL. Following the passing explosion in 94-96, offensive passing totals were pretty stagnant between 1997-2002.
The NFL has been a decidedly different game ever since totals bumped between 2003-2004 and then similarly in 2007-2008. For the first time since the eighties, we can accept seven yards per attempt to be the standard for passing. But even then, passing wasn’t necessarily efficient. It was simply accepted in the 80s that 4ish percent of a QBs passes were going to get picked. As it became wise to start trading some raw yardage efficiency to take fewer negative plays (sacks, picks), defenses caught up. But teams got really good at maximizing sack and interception efficiency in the mid nineties to early aughts to the point where passing became an equal or superior option to running the football league wide. And as the quality of the talent pool saturated with passing and receiving talent after the 2002 season
Back to the top, NYPA isn’t a great measure of era strength, perhaps because it’s too predictive of a measure. Young players who did average in NYPA typically played a lot more above average years. Old players who were average in NYPA were near the end of their careers. It wasn’t easily sortable to the point where the raw number gave a great snapshot of how passers were doing in that season. I will point out that Adjusted Net Yards Per Attempt correlates almost perfectly with the time horizon examined in this article.
Everything I learned here suggests that passing cycles are cyclical: predictive efficiency (NYPA) ended up as not a great measure of era efficiency because of sample size issues. Adjusting for interceptions and touchdowns fixes the variance in the sample and shows a long-term linear trend in passing efficiency. That’s fascinating because it suggests that as offenses have gotten smarter over the years, the defenses have been unable to force offenses (as a group) to negatively trade off points or yards. For example: it suggests that defenses are helpless to try to swing offensive efficiency in the other direction by increasing sacks or interceptions or passing touchdowns at the cost of yards against.
And despite this, NYPA was identical in 1979 as it was in the 2000s. The Blount rules had a huge, unbreakable effect on average NYPA, broken only by the unprecedented efficiency in passing we are seeing in the NFL since 2008. Overall leaguewide passing efficiency, however, started a steady climb then and was undeterred on a league level throughout fluctuations in yard and points expectancy. Scoring totals, keep in mind, correlate almost perfectly with passing YPA because increased INTs and Sacks (things not captured in YPA) don’t discourage scoring overall, they encourage scores by the defense.
The passing era of the modern (since 2007) NFL is historically unprecedented. Offenses have never been more efficient, and defenses have never had less of an effect on overall offensive efficiency. We’re now seeing 30-year long offensive efficiency rates begin to break in the offenses favor. This is exciting stuff if you happen to be a football history buff. Despite the sky high offensive efficiency rates, scoring totals will never match the levels of the 1950’s and 1960’s because offenses are now able to keep defensive scoring to a historical minimum. Despite that, teams are now scoring as much as they did in the 1980’s, when the passing environment was fertile, but also led to high turnover totals and short fields for the other team. Net yards per passing attempt really didn’t predict any of this: it said pretty much the same thing about offensive power from 1978 through 2006: 5.8 or 5.9 net yards a play. In the future, however, it might be the best indicator we will have to go on.
All statistics used in this article are courtesy of profootballreference.com