The 5th Commandment
Yards per pass attempt (YPA) is the success rate of the combination of play design and play-making
Cold Hard Football Facts has recognized that yards per pass attempt (YPA) is a "quality stat" because YPA "has a direct correlation to winning football games."
As further explained by the 6th Commandment and 7th Commandment, YPA is the measure of total offensive efficiency. YPA tells you not how much yardage your offense has gained; YPA tells you how well your offense is gaining yardage. YPA is not a quantity; YPA is a quality. Thus, unlike quantity statistics such as passing yards, which only tell you what has happened in the past, YPA provides an indication as to what you can rationally expect in the future on any down that the offense attempts to pass.
YPA clearly is the result of the combination of play design and play-making. "We devised plays to eliminate everyone but the man covering Jerry Rice," Walsh once said. "That matchup we'd virtually always win." In 1989, San Francisco created and won so many matchups that the 49ers posted an all-time best 9.491 YPA.
WHY is YPA the measure of offensive efficiency and not yards per rush attempt (YRA) or yards per play (YPP)? Concededly, the answer is not perfectly clear. The offense has two options available to meet its need to attain a first down: a pass or a run. Historically, even relatively inefficient teams have YPAs that are greater than the best YRA of all-time (1963 Cleveland Browns, 5.7 YRA). In addition, even the best run defenses (3 YRA) on average yield as many yards as the worst rushing teams can expect to gain on a given play (again, 3 YRA). This data indicates that if an offense passes well, it is unlikely that even the best defense will be able to prevent the offense from making a first down even if the pass does not by itself result in a first down. In addition, even if the offense passes poorly, it is unlikely that the offense will be any worse off than if the offense ran superbly. Thus, risk/return considerations suggest that independent of circumstances passing is more efficient than running.
Paradoxically, however, history appears to indicate that the more an offense runs the ball, the better the offense will pass the ball as measured by YPA. For a thoughtful discussion of the passing paradox, please see advancednflstats.com's series, The Passing Paradox, Part 1, Part 2, and Part 3. Advancednflstats.com also has found that the converse is true: YPA decreases as passing becomes more predictable.
As the table below demonstrates, as measured by YPA, Lombardi's running Packers were better passers than Walsh's passing 49ers. Bart Starr ranks 8th all-time in career YPA while Joe Montana ranks 20th all-time.
Unlike Montana and the 49ers, Starr and the Packers did not have the luxury of subsequent rule changes such as the "one bump" rule that were designed for the benefit of the passing game. Green Bay also played their home games in a place where weather was more likely to negatively impact the passing game, at least later in the season, than San Francisco did. Finally, Green Bay's footballs did not have the current Ultra Pebble design leather, which made the football easier to grip and which Wilson introduced in 1981 in the Walsh Era.
On the other hand, the Packers did not face the technologically advanced defenses devised by Chuck Noll and Bud Carson (Steel Curtain), Bill Belichick (Tight End Jamming 2 Deep Zone), Dick LeBeau (Zone Blitz), and Tony Dungy and Monte Kiffin (Tampa 2) that the 49ers faced.
League-wide, the two best seasons for YPA since 1960 occurred in the heart of the Lombardi Era: 1962 (7.445 YPA) and 1963 (7.339). And, as Cold Hard Football Facts has recognized, those numbers would have been even better if not for the commencement of the AFL, which passed more often than the NFL, but not nearly as well. [It should be noted, however, that the AFL's most efficient QBs--George Blanda (1961), Len Dawson (1962), Tobin Rote (1963), Jack Kemp (1964), John Hadl (1965), Dawson (1966), Joe Namath (1967), Dawson (1968), and Greg Cook (1969)--passed as well, and sometimes better, than their counterparts in the NFL.]
League-wide, teams did enjoy a brief period from 1982-1984, the heart of the Walsh Era, when league-wide YPA approached the figures posted during the heart of the Lombardi Era. But, again, liberalized passing rules also began to have an impact. Since the end of the Walsh Era, league-wide YPA has never come close to approaching league-wide YPA during the Lombardi Era.
In The Passing Paradox, advancednflstats.com suggests that perhaps winning (i.e., leading) in a NFL football game produces more rushing attempts, rather than more rushing attempts producing winning. This "chicken or the egg" question is a good one that QC will not attempt to answer definitively. Suffice to say that QC finds a comparison of the Packers' YPA to the 49ers' YPA to be convincing evidence, although anecdotal, that more running in fact produces better YPA (i.e., better efficiency and productivity) and thus more winning.
There can be no dispute that Lombardi's Packers ran far more often than they passed. Under Lombardi, Green Bay consistently ranked at the top of the league in rushing attempts and at the bottom of the league in passing attempts. Lombardi's design was known as "run-to-daylight." His bread-and-butter play was the power sweep. His own book was entitled Run To Win. Finally, future Hall-of-Fame coach Hank Stram remembered his first meeting with Lombardi while Stram was an assistant coach at Purdue. In 1954, Purdue upset Notre Dame, 26-14, behind 4 TD passes from Stram's sophomore QB, future Hall-of-Famer Len Dawson, and Lombardi came to West Lafayette to learn about Purdue's offensive design. In They're Playing My Game, Stram described the encounter:
"Using a blackboard, I attempted to describe our passing game. To my utter surprise, he had no more interest in it than the man in the moon. All he wanted to talk about was running strategies. He had a revolutionary scheme, he said.
'From a full-house backfield, all three backs go to the same side. All three attack to the left, or to the right. The halfback dives, the fullback goes off tackle, and the remaining back goes to the outside.' He beamed his odd smile at me. 'Nobody will know ahead of time who is to get the ball.' This to enhance the faking by the backs. [QC Note: Conceptually, Lombardi's revolutionary design was very similar to the Wishbone Triple Option design, the ultimate run-to-daylight design, invented by Emory Bellard and Darrell Royal at Texas in 1968.]
Running, that's all he wanted to talk about. I had a hell of a time trying to wedge in my explanation of how we had beaten Notre Dame with our passing game. He would wrest the chalk back from me and resume his passionate diatribe on the nuances of his revoluationary sweep. I took back the chalk and tried expounding on the pass. It was like a Marx Brothers comedy. We went back and forth like that all day."
"Defensive YPA" (DYPA) is a "quality statistic" that
defines the ability of a team's defense to render the opponent's offense
inefficient. The 2009 Super Bowl Champion Pittsburgh Steelers led the NFL with
an outstanding 5.37 DYPA.
Calculating YPA involves several choices. The first choice involves how, if at all, to account for sacks in YPA. Cold Hard Football Facts counts sacks as attempts and subtracts sack yardarge from passing yardage to calculate YPA. But a sack is not really a pass attempt. Rather, if one is precise, a sack is an attempt to attempt a pass. A sack is pass attempt prevention. Thus, yardage lost on sacks is really attempt prevention yardage (APY), which is YPA backwards, and sacks should not be counted as pass attempts.
On the other hand, sacks cost the offense a down and APY is the measure of pressure in units of yards and, unlike turnovers (see 9th Commandment), pressure can be designed. LeBeau, the inventor of the zone blitz said, "What you're trying to do is just change the look for the quarterback so that he does not sit back there and establish rhythm. We have all seen quarterbacks when they're toiling at this level. Offensively, they're trying to get into rhythm. Defensively, we're trying to keep them out of it. And that's where pressure is important."
For this reason, APY should be accounted for in YPA. But this yardage should not be accounted for by simply subtracting APY from YPA. A sack is like passing yards. A sack tells you how much yardage your team lost on a passing play, not how well your team is avoiding such a loss of yardage. Thus, subtracting sack yardarge from passing yardage only tells you what has happened in the past, it does not tell you what you can rationally expect in the future. To determine what an offense can rationally expect in the future, one must first calculate YPA, then divide APY by total pass attempts (again, not counting the sacks themselves as attempts), and finally subtract the average APY lost from YPA. Only by accounting for sacks in this manner can one quantify in units of yards the pressure that the offense is getting from the defense on every play. All references to "(QCAPY)" in QC's statistics mean average APY.
In addition, average APY accounts for negative passing yardage as a team accomplishment rather than as an individual accomplishment. "'The sack was never meant to be an individual record,'" said Seymour Siwoff of the Elias Sports Bureau, the leagues statistical arm, in Tom Danyluk's Pro Football Weekly story, Sackmaster Bubba Baker's amazing rookie season. "'Its the result of a whole defensive unit working together to get the quarterback. We never felt one player should be given all the credit.'"
That all changed as the leagues coffers began to swell and players demanded a bigger piece of the money pie. Individual statistics were increasingly being wrapped into player payout. Agents were becoming more creative in their contract demands. Clauses incentives bonuses It was the onset of the "Me" generation.
"'Ill never forget this,'" said Siwoff. "'One time I ran into [former Raiders executive] Al LoCasale, back around 1981. I said, Al, I dont get it. Im getting all these phone calls about statistics, guys calling me up, griping about one yard on a special-teams play, things like that. Why are they doing this? " "'Bonuses,'" he said. "'More and more contracts have performance clauses tied into them. And its not going away.'"
And so, suddenly, the individual sack statistic was created.
Aside from APY/sacks,
the second choice QC makes in calculating YPA is QC does count spikes and other
attempts by quarterbacks the purpose of which is to stop the clock, rather than
complete a pass, because such intentional incomplete passes do have an
offensive purpose (preserve future chances). Also, on intentional incomplete
passes, the defense takes a down. Thus, all incompletions have a cost (a down)
and should be counted irrespective of the intent behind the incompletion.
Because calculating YPA involves these choices, QC provides "Traditional YPA" (which does not count sacks as attempts or subtract sack yardarge from passing yardage or add 10 yards for TDs) and "QCYPA" (which does not count sacks as attempts, subtracts average APY from YPA, and adds 10 yards for each TD pass). However, QC calculates efficiency and productivity using only QCYPA.