Play Calling on 3rd and Short Part 3

In this third and final installment looking at play calling on third down, I'll analyze the statistical relationship between individual team's tendencies and their conversion rate. So far, in part 1 and part 2, we've seen that running on 3rd and short tends to get more first downs and leads to scoring more points. So, are individual teams that tend to run on third and short more successful than teams that tend to pass?

A Case Study

One of the notable differences between Patriots’ coach Bill Belichick and most other coaches is his tendency to run on 3rd and short. I cannot recall where I read that, and I’ve wanted to examine 1—if its true, and 2—how it affects his team’s success on third down.

First, yes, it is true. In his tenure with the Patriots, Belichick has run 80% of the time on 3rd and 1 compared to a league-wide average of 70%. This rate makes the Pats tied for 3rd in the NFL for run tendency in that time frame. Their overall conversion rate for all 3rd down and 1 situations was 5th in the league at 72%. So Belichick’s reputation is at least partially true. His teams are near the top of the league in both categories, but not at the very top.

But what about the rest of the teams? If there is a statistical link between run tendency and conversion rate across the NFL, this would be confirmation that teams should run more often on 3rd and short.

The correlation between percentage of run attempts and conversion rate on 3rd and 1 situations is 0.19 (which is statistically significant at p<0.01, n=254.) This seems pretty big considering all the factors that go into conversion rate—team strength, opponent strength, luck. Simply calling more run plays would significantly improve most teams’ conversion rates on 3rd and short. The effect may be somewhat overstated, however. Not all 3rd and 1s are equal. Both 3rd and 1 inch, and 3rd and 1½ yards are considered ‘3rd and 1’ according to the NFL. So teams that have a disproportionate number of 3rd and 1 inch situations would logically run more often, and more successfully. But any bias in the correlation would likely be very small as there are over 28,000 3rd and 1 plays in the data set, and any effect should even out among teams. Additionally, 3rd and 2 and 3rd and 3 situations do not exhibit that complication, but the evidence that teams pass too often is just as strong if not stronger.

The total of all the evidence makes the conclusion clear. Offenses should run more often on 3rd and short. Based on conversion rate, expected points, and team-by-team correlation, running more often on third and short leads to more 1st downs, more points, and consequently more wins.

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5 Responses to “Play Calling on 3rd and Short Part 3”

  1. Dr Obvious says:

    A big chart with team name, run rate on 3rd and 1, and conversion of 3 and 1 would be very useful...

  2. Brian Burke says:

    Doc-That would be a pretty big table with 252 rows. Perhaps I can add a table of the top few and bottom few teams.

  3. John Vetsch says:

    Quote from Dr. Obvious -
    "A big chart with team name, run rate on 3rd and 1, and conversion of 3 and 1 would be very useful..."

    I was just looking for such a stat as well. Advancednflstats, are you on it?

  4. Ian says:

    Just read this series. Interesting stuff. If you're correct then there should be, theoretically at least, teams that also run too often on 3rd and 1 and adversely affect their conversion %. Is there a chance of a graph showing each of the 32 teams 'run on 3rd and 1 %' and 'conversion %' over the 7 years?

    In the real life data we might not see evidence of teams overrunning the ball on 3rd and 1 because none of them is at equilibrium.

  5. Robbie says:

    Please forward this post to one Mr. Bruce Arians.

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