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# NFL Analysis: Long vs. Short Passes

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Over the past couple years, we've learned that passing well is  more important than running well in terms of winning games.

We've learned that passing has become more and more lucrative over the years. And we've learned that offenses should pass more often, particularly outside the red zone and on 1st down. But 'passing' is a large category, encompassing everything from a screen pass 2 yards behind the line of scrimmage to a 50 yard bomb.

Beginning in 2006, the NFL classified every pass attempt as either 'short' or 'deep,' where deep means anything past 15 yards. About 19% of pass attempts are classified as deep.

Unfortunately, that's all we get, so we can't tell a screen from a 14-yard down-field pass attempt. Still, it allows us to begin to pull apart different types of passes and examine them in one more layer of detail.

In normal football situations, in which the clock is not yet a factor and the score is relatively close, pass plays, including sacks, yield an average of +0.08 Expected Points Added (EPA), while run plays yield an average of +0.01 EPA. Which type of pass is more responsible for that advantage, risky deep passes or safer short passes?

Let's compare the value of short and deep pass attempts, limited to normal situations (1st and 3rd quarters, the score within 10 points) and outside the 15-yard line. (It's difficult to throw a deep pass inside the 15.)

 Pass Depth Avg EPA Success Rate Short -0.01 47% Deep +0.45 43%

Deep pass attempts average +0.45 EPA, and short pass attempts average -0.01 EPA. However, short pass attempts are more likely to be 'successful,' defined as more likely to result in a positive EPA. Short passes in the sample are successful on 47% of attempts, and long passes are successful on 43% of attempts.

It's important to note some serious limitations of a direct comparison between deep and short passes. First, any pass attempt means that several things have already gone well. The pass protection held up long enough to allow a throw, and a receiver and a passing lane was judged to be open. Deeper pass attempts naturally require more time to develop, so the pass protection must last longer.

Deeper pass attempts have a higher risk of interception. Deep attempts are intercepted 6.4% of the time, compared to only 1.8% for short attempts. Deep attempts certainly are riskier, but the risk of interception is already baked into the respective EPA values of deep and short attempts.

It's the additional risk of a sack that makes the comparison tricky. About 6% of pass plays result in sacks. Unfortunately, there is no way to tell whether a play that resulted in a sack was drawn up as a deep pass play or not. We can't directly measure the increased risks of deep attempts due to sacks, but we can attack the question from a different direction.

In the data sample (normal situations from 2006 through 2009), there were 4,609 deep attempts worth a total of +2,084 EPA. There were also 1,464 sacks (including sack-fumbles) costing a total of -1,985 EPA. So even if every single sack were due to a play drawn up with a deep route as the primary target and we count it against the deep category, the deep attempt still comes out as a net positive.

The deep pass is probably an underused tactic by current NFL offenses, but this does not mean that every team should immediately start heaving the ball down the field. Obviously, given the choice between a deep and short pass, teams would prefer deeper passes. The problem is that not all teams have that option, either due to pass protection or receiver abilities. There is a large bias in the results above, because the offenses that do throw deep often are likely to be the offenses that throw deep well. Additionally, many short passes are 'check-downs' to a safety-valve receiver, typically a back, when the deeper routes are covered. This is a murky topic without clear answers.

Still, I think there is something to be learned here. All things considered, short pass attempts yield a net negative average EPA. Run plays average a better EPA than short attempts. It's not simply that passing has generally superior payoffs than running. It's that the entire advantage of modern passing comes from deep passes. Teams should probably be passing deep more often, and running and passing short less often.

I suspect the culprit isn't the 8- to 15-yard 'short' passes, it's the really short stuff. I wonder if all those quick-out WR screens are just wastes of downs. I realize they are often intended as 'constraint' plays designed to keep the defense honest. But they rarely seem to be very successful. We'll need a lot more detailed data to really understand what types of pass attempts are most and least productive.

Sure, every team would like to throw down-field more often, but only some are able. The lesson for GMs and coaches is: become one of those teams. 'Easier said than done' would be an understatement, but it's well past the time when teams should be building predominantly around the run or thinking that high percentage short passes can replace a real down-field threat. Teams should invest in draft picks and free-agents who can consistently get large chunks of yards, and invest in the practice time needed to perfect deep routes. And if you already are one of those teams who can throw deep, you should probably do it more often.

You can try to march 70 yards down the field-- 3, 5, or 7 yards at a time--allowing the defense ample opportunities to force a punt, all the while hoping not to commit a turnover. Or, you can go for large chunks of yards 15, 20, or more at a time. Sure, it's riskier on any single given play, but the numbers suggest that's where the advantage is.