The NFL and the run on 2nd and long

 Over the past decade, the NFL has become a passing league.  QBs  today throw more often and more efficiently than at any point in the past.  As such, the thinking around playcalling has shifted t emphasize this.  The analytics community and more and more coaches are looking at what had long been a staple: the run on second and long.  What in the past had been an expected play to try and set up a manageable third down has become a place where teams throw to try and convert.  In 2015, teams threw 4165 passes on 2nd down, 7+ yards to go in standard time (non blowouts and not the last two minutes of the half).  They ran in those situations 1865 times.  Last year, the share had grown to 4658 pass attempts to just 1829 runs.  Overall in the 2015 through week 10 this year, teams have had successful plays on 40.7% of those pass attempts.  And it would seem that that's the right choice, since the success rates on those run plays has only been at 28.7%.  Using the Fisher Exact test, we can confirm that there is a statistical difference, and that teams are in fact getting more from passing in those situations.  On just a per play basis, passing plays gained ~6 yards to run plays 4 yards. Unsurprisingly, teams also pick up a first down on a greater number of pass plays than running it, roughly by a 2:1 margin.

This doesnt mean passing doesn't have its own risks.  The havoc rate when dropping back to pass over the period was around 14%, to just 10% for running plays.  And teams were much more likely to get at least one yard running the ball vs throwing, by about 20%.  Comparing the success rate from 2015 to last season, there also appears to be a statistically significant drop, from 40.6% to 39.7% on a greater volume, although the havoc rate did drop significantly.  Run plays did see their success rate rise by roughly 2% in that time as well, and also had a 2% drop in havoc rate. This year so far both plays have seen a significant uptick, as it appears offenses are just outpacing defenses overall.

The run on 2nd and long isn't dead, but its fairly easy to see why teams have started to lean more heavily on throwing in those situations.  The huge jump in success rate is keeping offenses on schedule more often and that is leading to better outcomes.  Its especially true for teams that have low havoc rates.  There will be trends to watch of course, as defenses continue to try and find ways to stop passing games more efficiently, which perhaps will lead to a renaissance of runs.  But for now, passing remains king.