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Quick Hit: Offensive Points Per Game

November 23, 2011 Leave a comment

One of the big misconceptions people have about today’s NFL is that there are significantly more points scored than ever before. However, that’s just not true. You’d have to go all the way back to World War II era football to find a time when there were significantly fewer points scored per game. Since about 1950, average points per game (per team)  has stayed between 18-22. Here’s how it looks since the AFL/NFL merger in 1970:

As you can see, today’s offensive scoring is on par with what we saw for most of the last 30 years and only a little higher than the 1970’s. If the NFL had a “dead ball” era, it was the early 1990’s where offensive scoring dropped from 18.7 PPG in 1990 to 17.7 in 1991, 17.04 in 1992 and 17.9 in 1993 before jumping back up to 19.0 in 1994. A similar drop occurred in 1977 when scoring when from 18.3 PPG to 16.0.

Taking a look at it by source of points:

Each line represents the average number of offensive points per game by source of score. What happened in the early 1990’s was a one year drop in pass TD. In 1990 each team scored an average of 9.3 points off passing TD’s (and extra points) and 6.5 PPG from rushing TD’s. In 1991 that dropped to 7.9 passing PPG and 5.7 rushing PPG. The next two years saw passing TD’s rebound, 8.6 PPG in both 1992 and 1993 but rushing PPG fall to a mere 5.0 PPG (both years). In 1994, things normalized again, passing PPG jumping to 9.2 and rushing PPG to 5.7. Rushing PPG has only gone over 6.0 twice since 1990 (6.3 in 2002 and 6.4 in 2008).

Where are we so far in 2011? Well, through Week 10:

While this is being called the “Year Of The QB” (with some merit to that claim), passing TD’s are down from last year – and that’s before the harsh weather starts setting in.

So, while the media plays up the offensive “explosion” we have seen this year (and in the last 2-3 years), overall offensive scoring hasn’t seen too much change in 30-40 years other than a few isolated short periods.

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Categories: Stats Tags: , ,

The Effect Of Pass/Run Ratio On Offensive Production

November 1, 2011 Leave a comment

In 1970, the average team threw the ball on just 48% of their offensive plays. In 2010, that number had risen to 56.9%.  The average points per game per team has risen from 19.3 to 22.0. Therefore, the assumption is that more passes = more points. But that’s not necessarily the whole story. Here are the average pass play percentages since 1970:

And here is the average points per game:

As you can see, the increase in points per game doesn’t exactly follow the increase in passing, most noticeably between 1990-1995.

What’s interesting is that there is a strong correlation between pass play percentage and yards per drive:

Over the last 40 years, offenses which pass more than they run tend to generate more yards per drive (YPD). Which makes sense since the average yards-per-attempt is higher for pass plays than it is for rushing plays . In 2010, the average Net Yards Per Pass Attempt [(pass yards-sack yards)/(pass attempts+times sacked)] was 5.7 and the average Yards Per Rush was 4.2.

The trendline is approximately (since we’re dealing with rounded numbers) defined as YPD=14.93(Pass%)+21.01

However, the additional yards gained from passing doesn’t pay off in as many points as you’d think:

Here we see a much looser correlation between the number of pass plays a team runs and the average points per drive (PPD). The trendline is PPD=.111(Pass%)+1.66. Here are the top 20 point-per-drive teams since 1970:

There’s an interesting mix of offenses here. The 2006 Chargers and 2008 Saints had identical PPD but San Diego threw the ball 13.37% less frequently. Four of the top 5 threw the ball less than 60% of the time.

There are a couple things which are going on here. First, teams which score a lot of points tend to run more towards the end of the game to chew up clock (as many of those teams would have built large leads). So they may throw 60% of the time in the first 3 quarters and then run the ball 70% of the time in the 4th quarter. Conversely, teams who don’t score as many points are probably more often in the position where they have to throw a lot to catch up in games – thereby inflating their pass% slightly.

Later this week, I’ll take a look at defensive performance and see if there is any tie between a team’s defensive efficiency and their offense’s pass/run ratio.

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