I don't know if you've followed any of the analysis on run-pass balance on Advanced NFL Stats, but it very interesting. For many teams, running the ball is a wasted down.

http://www.advancednflstats.com/sear...ax-results=100

(links within the articles are worth tracking down too).

The article on historical analysis of run-pass balance was particularly good.

http://www.advancednflstats.com/2010...-analysis.html

Especially this passage:

If it the above conjecture about run defense inelasticity is accurate, rule changes would be the only way to restore run-pass balance to the game.

I haven't read that, but it's on my list. It sounds quite interesting.

In 1984, teams averaged 1.37 TD passes per game.
Last year, teams averaged 1.47 TD passes per game.

What a huge change there's been.

The average passing yards per team has risen from 3,294 to 3,770 from 1984 through 2013. That averages 30 yards more per game, which I think is significant. (The average went from 206 to 236.)

Honestly, I would have assumed that the averages were much higher than that on yardage, and also that the increase would have been larger. Must be a Matt Cassel effect in 2013.

I'm also showing 1.57 TD passes per game in 2013. If it was 1.37 in 1984 and 1.47 in 2012, then we saw a 30-year jump in average over the course of a single season in 2013. I'm not bothering to calculate all the years in between, so maybe one of the three numbers is a fluke.

Pre-calculated easy-to-compare data:

http://www.pro-football-reference.co...team_stats.htm

That was much easier than my way.

Wow, the passing data is really interesting. I wonder what happened in 1947 to throw the yardage numbers up so quickly. I don't think it would be AAFC thing, because I don't think their stats are included in NFL stats. And then around 1968 they hit the skids, and again I'm not sure why. There's likely an AFL effect, but the pattern doesn't seem to match exactly.

You have the same bulge in TD passes per game, which again doesn't exactly match the AFL era or the AAFC era. How weird.

Some speculation on reasons are here:

http://www.advancednflstats.com/2010...-analysis.html

That portends that passing is going to become even more dominant as coaches slowly pick up on the various new rules about touching receivers and hitting receivers.

Do they include PI yardage in offensive stats ?

Nope.

They should include all PI as stats for the offense, did they gain the yardage or not?

If your going to throw the flag and award one team 45 yards for a passing play, it should be counted as offensive yards.

This would make the stats a lot different,

I'm really curious what happened in 1947. The per-game passing and scoring both jumped dramatically, but I see no substantive rules changes.

Here are the scoring stats by year: http://www.pro-football-reference.co...FL/scoring.htm

The 1948 season was the highest-scoring in NFL history on a per-game basis, even higher than 2013 (which is the second-highest). The top ten scoring seasons in NFL history are:

1948 - 23.6 ppg.
2013 - 23.4 ppg.
1965 - 23.1 ppg.
1950 - 22.9 ppg.
2012 - 22.8 ppg.
1949 - 22.7 ppg.
1958 - 22.6 ppg.
1952, 1962 - 22.3 ppg.
2011 - 22.2 ppg.
1947, 1963, 1964, 2008, 2010 - 22.0 ppg.

So we've had three offensive ice ages in the history of the NFL - a five-season stretch from 1947-1952, a four-season stretch from 1962-1965, and a current six-season stretch from 2008-2013 and counting.

Wikipedia lists the following rules changes in 1947. None of them would account for a huge 10+% increase in scoring. That increase was abrupt, and it was bigger than the increase we saw with the 1978 major rule changes.

A fifth official, the Back Judge, is added to the officiating crew.
When a team has less than 11 players on the field prior to a snap or kick, the officials are not to notify them.
An illegal use of hands penalty will be called whenever a defensive player uses them to block the vision of a receiver during any pass behind the offensive team's line.
During an unsuccessful extra point attempt, the play becomes dead as soon as failure is evident.
Roughing the kicker will not be called if he kicks after recovering a loose ball or fumble on the play.
All teams are required to use prescribed standard yardage chains, down boxes, and flexible shaft markers.
Games are no longer played on Tuesdays.

In 1962, wikipedia lists only one major rule change, which likely helped the running game a fair bit.

Grabbing any player's facemask is prohibited.


Here's an interesting article about NFL scoring: http://www.coldhardfootballfacts.com...l-orgasm/7392/

They propose an interesting counterintuitive theory about scoring in the late 40s, noting that there were many more turnovers then, which may have given offenses short fields. I don't think that explains the sudden increase, though.

There's also a minor implication that perhaps if kickers weren't as good, teams pushed for touchdowns more often. That makes sense to me.

They also showed this chart of scoring by decade, which shows the 1960s as being the full decade with the highest average scoring. That's mindblowing considering it was the era of the middle linebacker.

1960s – 21.7 PPG (NFL only)
1950s – 21.5 PPG
2000s – 21.0 PPG
1980s – 20.9 PPG
1990s – 20.2 PPG
1970s – 19.2 PPG
1940s – 19.0 PPG (NFL only)
1930s – 11.4 PPG
1920s – 9.4 PPG

So far in the 2010s, the average scoring per game is at 22.6 and on an upward trajectory. So we're definitely in the highest-scoring era in history.

I would agree.

Considering individual teams from the 2013 season, there was no significant correlation between passing yards and first downs by penalty, which seems to argue against the "chuck it down the field and hope you draw a PI penalty" offensive strategy being prevalent in the league.

There also doesn't seem to be a tend in number of first downs awarded by penalty. They are currently on a 6 year upward trend but within the norm of the last 30 years of trends.