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The Effect Of Pass/Run Ratio On Offensive Production

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.