What’s going on with passing? Is it higher completion percentage? Is it deeper passes? Is it simply more pass attempts? Let’s take a closer look at the numbers to get a better idea of what might be causing the dramatic increase.
Before I get to my theories, I’m going to throw a bunch of graphs at you. Each graph looks at one or more dimension of the passing game by year. Pay close attention to the axis numbers on the left side of each graph so you’re not deceived by varying scales. First, let’s look at Expected Points Added per Play (EPA/P). This combines all the other stats into one understandable number representing the net point differential gained or lost by each pass play. This includes sacks, penalties, turnovers, and everything else. This will give us an overall idea of passing’s relative potency over the past decade.
Next, let’s look at net Yards Per Attempt (Net YPA). This is a very handy stat for getting a feel for the level of passing success throughout the league. Notice the dramatic increase from last year to this year.
Next up are sack and interception rates. With all the passing going on, the downside could be an extra exposure to passing’s inherent risks. But instead, we see a steady decline in sack and interception rates, and this season the trend is continuing.
What about the number of pass attempts? Here we see that teams are (correctly) passing more often each game by about 1.5 more attempts per game by each offense. The number of attempts looks relatively steady until a couple years ago, when it began a noticeable climb.
Next, lets look at yards per reception. You'll notice this graph closely mimics YPA. This season, YPR has dramatically increased right along with YPA. This suggests that the increase in total yards is due to more yards gained on completions rather than more completions.
The next graph shows the long-term increase in both completion percentage and passing success rate (SR). However, completion percentage isn't appreciably higher than it was in recent seasons.
So if YPR is increasing, and completion percentage is about the same as it's been, QBs must be throwing deeper, right? Data in this category only goes back through 2006, but we still see a discernable trend. Contrary to what we'd expect, the trend is downward. Teams are attempting fewer deep passes, and so far 2011 has the lowest deep attempt rate of recent seasons, slightly shy of 19%.
Yards are up. Yards per completion are up. Yards per reception are up. Completion percentage is level. Deep passes are slightly down. Sacks are down. Interceptions are down. So how do offenses increase yards per reception without throwing deeper? The answer is Yards After Catch (YAC).
YAC is way up. Last season offenses averaged 110 yards of YAC per game. This season, they're averaging 123. In 2010, YAC comprised 48% of all passing yards, and so far in 2011, YAC comprises 53% of all passing yards.
Further, teams are responding to the increased effectiveness of the pass by passing more often. This compounds the effect, resulting in the record setting torrent of total passing yards we've witnessed.
If I had to guess, the underlying cause is the rise of the screen pass. High YAC percentage usually comes from screens and check downs. I don't have data on pass types, but the guys at ESPN do. I bet we're seeing more and more screens, particularly WR screens where one receiver runs a 'pick' pattern. At least, that's what I've noticed with just my two eyeballs.
I've heard many commentators suggest the lockout has somehow had more severe effects on complex pass coverage schemes. I can't rule that out, but it seems like an easy, lazy conjecture--impossible to prove and impossible to reject. If passing were dramatically down this season, the very same commentators would be saying that the lack of off-season practice disproportionately affected complex passing offenses. If field goal percentage were down, they'd say the same thing about kickers and holders, too.
For those, like myself, who were waiting to see these passing numbers regress to the mean as the season goes on, we shouldn't hold our breath. This season is part of a long-term trend in passing in the NFL. It may in fact regress to some degree, but the true mean of today's NFL is not necessarily last season's numbers or an average of the last several seasons. The game continues to change.