For some, "air yards" might be a silly phrase you've seen but don't really understand. For others, it's a stat that has become part of your typical research.
Regardless of where you fall on the spectrum, I'm here to tell you air yards aren't going anywhere, and you should be paying attention to them.
Since it's still a relatively new stat, and since it's measured a couple different ways at different sites, let's go over the terminology I will use in this article. On any given pass, "air yards" are defined as the difference between the line of scrimmage and the yard line where the ball got to the receiver. It doesn't matter how deep the quarterback's drop is. It doesn't matter if the ball is caught. It doesn't matter if the throw is directly over the middle or a much longer throw to the sideline.
If it's first-and-10 and the throw is to the sticks, there are 10 air yards on that play. If it's a quick-hitter caught 2 yards behind the line of scrimmage, it counts for (-2) air yards. If a receiver got both of those targets on consecutive plays, he'd have two targets for 8 air yards. His average depth of target (aDOT), which is air yards divided by targets, would be four.
Why do air yards matter?
Before 1992, targets weren't tracked. Today, we reference targets in nearly every piece of Fantasy Football content.
And targets are great! On their own, targets are more predictive than air yards. But air yards are simply a second measure of receiving opportunity. That's why we count them whether the pass is caught or goes incomplete, just like targets.
Air yards are to receiving yards what targets are to receptions. Targets measure the number of potential receptions a player could have accumulated if they caught 100% of the passes directed at them. Air yards represent the number of potential receiving yards a player could have gained if they caught 100% of the passes directed at them, not counting yards gained after the catch.
And two measures of opportunity are better than one. While targets are more predictive than air yards on their own, when used in conjunction, the combination of air yards and targets are more predictive than targets alone. Air yards add valuable context.
Some additional information
Here are a couple more things to consider about air yards, with much of the research from Josh Hermsmeyer, proprietor of airyards.com.
1. The deeper the target in terms of air yards, the lower the expected catch rate, and the higher the expected yards per catch
This is pretty self-explanatory, but it helps explain why speedy deep threats have very different catch rates and yards per target or yards per reception numbers than slot receivers who see more catchable targets at shorter depths.
This is where air yards can be very useful additional context beyond raw target numbers, particularly for the downfield targets. Deep threats who aren't producing but are still seeing five or so targets might rack up a lot of air yards, indicating potential yardage is there in the right matchup or if variance swings in the positive direction and they haul a few in.
2. You can break air yards into completed air yards and incomplete air yards
The main reason to look at things this way is to discuss yards after the catch. Standard receiving yards -- that old, trusted stat we count for Fantasy points and want to be able to predict -- can be broken into two components: completed air yards and yards after the catch.
Yards after the catch are highly variable, and not something to rely on. Short passes near the line of scrimmage do tend to generate more yards after the catch, on average, than deeper passes. But once we control for depth, yards after the catch are not a very predictive metric.
That is a big reason why air yards are so helpful, because they aren't as volatile as yards after the catch. And since a player's receiving yards are made up of those two elements, the completed air yards part is more helpful for our purposes as we try to forecast future production.
3. RACR is the air yards equivalent of yards per target
Continuing the comparison of targets and air yards as two separate measures of receiving opportunity, we can look at an efficiency metric created by Josh called RACR (Receiver Air Conversion Ratio).
RACR is a cooler name for "yards per air yard"; it is calculated the same as yards per target or yards per reception, but with air yards as the denominator. Josh has shown it's also a stickier efficiency metric than YPT or YPR, meaning more predictive.
4. WOPR is an opportunity metric that combines targets and air yards
Josh is a fan of acronyms, as you can see.
WOPR (Weighted Opportunity Rating) is one of my favorite Fantasy stats. It looks at a combination of a player's share of targets and share of air yards in his passing offense. It's weighted toward predicting Fantasy points, meaning target share gets more weight than air yards share because that's the most appropriate mix for predicting future Fantasy scoring.
But the important point is because both are included, it's more predictive of future performance than target share alone. This is a stat that does some of the work of incorporating the two opportunity metrics together.
One limitation is that because WOPR looks at the share of a player's offense, context needs to be added about team passing volume. Last year, Corey Davis had the league's eighth-highest WOPR, right behind Antonio Brown and Michael Thomas, whose teams had better second receiving options. We'll get into ways to apply air yards in an upcoming article.
You can find sortable data tables that include RACR and WOPR at airyards.com/tables.html.