Given the dearth of football news right now, I spent a little time looking at some of the commonly available stats to see which correlated most strongly with scoring. We all know that, when judging an offense, points scored by the offense is the most important stat. But my question was which other stats, if any, are good indications of how much an offense will score?
A few things don't correlate well with scoring:
- Run-pass balance. This bugaboo has almost no correlation at all with offensive points scored. It seems like lots of the highest scoring teams in the league pass a lot, but so do a lot of the lowest scoring teams.
- Basic rushing stats, like attempts, yards, and yards per carry. These have a weak correlation with scoring. The highest scoring teams have a slight tendency to get a bit more from their running game, but there are lots of exceptions.
Better correlations with scoring seem to be many of the passing statistics, including:
- Completion percentage
- Passing yards
- Low number of sacks given up
- Yards per completion
The absolute best correlations with scoring, though, are three yards statistics:
- Total yards. Good.
- Yards per play. Better.
- Net yards per pass play (accounting for incompletions and yards lost to sacks). Best.
What does this all mean? Well first, the tradition of measuring offenses and defenses by total yards does make sense, since total yards does correlate well with scoring. Second--and more significant--the high scoring teams are almost always high in net yards per pass play, while the lowest scoring teams almost always have low net yards per pass play. This suggests that the key to scoring on offense is to have a highly efficient passing game. Throwing a lot isn't necessary. But getting at least 6.0 and ideally close to (or more than) 7.0 net yards on your passing plays is critical. Net passing yards below 6.0 almost always means you are in the bottom of the league in scoring.
Statistically at least, an efficient passing game makes a productive offense.
Note: The "net yards per pass play" statistic is not one generally included in the stats summaries published by the various sports news outlets. Instead, most news outlets include "average yards per pass." The reported average is basically receiving yards divided by pass attempts. This accounts for incompletions, but not sacks. I calculate net yards per pass play by (1) subtracting yards lost to sacks from the receiving yards number--this equals the widely reported net passing yard number. Then (2), I divide this by the sum of pass attempts plus times sacked. Baisically, the reported average ignores sacks, but my stat includes them as passing plays.