"We learn more by looking for the answer to a question and not finding it than we do from learning the answer itself." -- Lloyd Alexander.
In Part 1 of this series, I took a look at the statement that the NFL is becoming a passing league. What we found was that from 1966 (the year of the first Super Bowl) to 2009, there was a general rise among the majority of teams in the passing yards produced each season. In the 1960s, the majority of the teams produced between 2500 and 2999 passing yards. By the 2000s, that number had risen to between 3500 and 3999 passing yards. While each year had ebbs and flows to where teams fell along the spectrum, 2009 saw a dramatic increase in passing production. In 2009, we saw 23 teams throw for 3000 yards or more. Of those 23, 15 threw for 3500 or more yards. 12 out of those 15 surpassed 4000 passing yards, and 2 of those threw for over 4500 yards. It remains to be seen if 2009 represents a new offensive trend in the NFL, or if was simply an aberrant spike in the productivity. At the end of Part 1, I posed the following question:
Is this slow but steady rise an indication that the teams are shift away from running the ball to a more pass oriented offense, or could it be that there is simply a greater emphasis on offense overall?
In this look at the changing face of the league, we will be addressing what has occurred with the rushing game, as the yards produced by the passing game have increased. We will be using the same divisions: 1966-69, 1970-79, 1980-89, 1990-99, and 2000-09. I'm not going to present team-by-team data, but rather look at the overall league data. The data will be presented in the form of how many teams amassed rushing yards in set categories. Those categories are: <999, 1000-1499, 1500-1999, 2000-2499, 2500-2999, and 3000+. What I found, is not what I expected to see.
I'll share what I found after the fold.
A quick reminder that this study has been arbitrarily restricted to the years 1966-2009 -- The Super Bowl Era. The goal was to see how the offensive production had changed during this time period. It is helpful to remember that although we have lumped the teams all together, the period of 1966-69 was during the time that the AFL and the NFL existed as separate entities.
We can see from this graphic that the overwhelming majority of the teams fell into the 1500-1999 rushing yardage range.
The 1970's were the early years of the AFL-NFL merger which gave us the AFC versus the NFC in the Super Bowl.
The early part of this decade saw the majority of the teams continue to fall into the 1500-1999 yard range. However, in the final 2 years of the 70s, we can see how teams became more effective at running the ball as the majority were now found in the 2000-2499 yard range.
Please remember that 1982 and 1987 were strike years, with 1982 playing a drastically shortened season and 1987 having 1 less game along with 3 games played by replacement players.
The 1990s were perhaps the most stable year for the rushing game, with next to no variation in the production of the teams.
The most recent decade was more or less simply a repeat of the 1990s.
1960s - majority fell in the 1500-1999 range1970-1977 - majority fell in the 1500-1999 range1978-79 - majority fell in the 2000-2499 range1980s - majority fell in the 1500-1999 range1990s - majority fell in the 1500-1999 range2000s - majority fell in the 1500-1999 range
1960s -- majority fell in the 2500-2999 range1970-78 -- majority fell in the 2000-2499 range1979 -- majority fell in the 2500-2999 range1980s -- majority fell in the 3000-3499 range1990-94 -- majority fell in the 3000-3499 range
1995 -- majority fell in the 3500-3999 range1996-99 -- majority fell in the 3000-3499 range2000 -- majority fell in the 2500-2999 range2001-09 -- majority fell in the 3000-3499
||Defenders are only allowed to make contact with receivers once
||Defenders may only make contact with receivers within 5 yards of the line of scrimmage
||Pass blockers are allowed to use extended arms and open hands
||Incidental contact and simultaneous attempts to catch, tip, block or bat the ball are no longer considered to be Pass Interference
||Pass Interference is no longer applicable to clearly balls which clearly cannot be caught
||Allows the QB to spike the ball to stop the clock
||Pass Interference in the end zone results in the ball being placed at the 1 yard line
||An eligible receiver forced out of bounds by a defender may return to the field and be the 1st offensive player to touch a forward pass
||Radio receivers are allowed in the QB's helmet
||When a receiver has possession and control of a forward pass and falls to the ground, the ball is allowed to touch the ground if the receiver maintains clear control
||Roughing the passer penalties are to be strictly enforced
||Illegal Contact, Pass Interference and Defensive Holding penalties are to be strictly enforced
||Catch Rule is changed to "control of the ball and 2 feet down inbounds" (A "football" move is no longer required to rule a pass as complete)
Prior to about 1966 the ration of run to pass was around run-60% and pass-40%. At this time, you gained more net yards per play, on average, by running, due to the diminishing effect on total passing yards that comes with INTs. But, continual changes in the passing game did bring up overall YPP over the intervening decades.
One of them, of course, was the work of Sid Gillman that led to the innovations of Bill Walsh. Unlike his friend on contemporary Don Coryell, Walsh refused to accept the problems created by interceptions, and his risk-phobic additions to the passing game still influence pro ball today. Many factors played in, perhaps none more heavily than the rules changing the meaning of offensive holding and those governing the amount of contact permitted by the defender on potential receivers. Over a thirty year period, the tendency moved from run-0dominant to pass dominant. I don’t the the exact numbers in my head, but a detailed discussion of this issue is found in the book The Blind Side.
There is an excellent article that looks at the run-to-pass ratio at advancedfnlstats.com: Run-Pass Balance--A Historical Analysis, by Brian Burke. Burke looks at the trends from 1940 to 2009. He looks at the yards per play from rushes compared to passes and the rushing plays vs the passing plays per game.
(graphs used by written permission from Brian Burke)
Burkes' research clearly shows that while the yards per rush had a minimal increase over the years, yards per pass has jumped dramatically -- particularly beginning in 1978. Burke also demonstrates -- as Emmett mentioned above -- the rushing plays per game game and the passing plays per game have reversed prevalence. Thus we seem to have a situation in which:
||The NFL has been stressing offensive production -- as indicated by both passing and rushing yards per play steadily increasing.
||The NFL has been stressing passing production -- as evidenced by the dramatic increase in passing yards per play since 1978.
||The increase in passing production has not come at the expense of rushing production -- rushing production has risen slightly and remained relatively steady, despite the increases in passing production.
||The increase in passing production appears to be the result of the increase in the number of passing plays per game, along with rules changes that favor the passing offense.
||Rushing production appears to be becoming more efficient, as evidenced by the fact that despite a decline of nearly 10 rushing plays per game since 1979, rushing production has remained relatively stable.
With this emphasis on offense, and on passing in particular, the next question quickly becomes: