Of these two major sports American sports leagues, the National Football League has undoubtedly been the slowest to embrace analytics. This may be true because of a combination of factors. NFL games and football in general possesses more randomness due among other things, a small sample of games in a season, a lack of a postseason series, and the number of players doing different actions in any given play can lead to several outcomes that may be hard to predict and hard to detect any sort of true value. Above this, there is a strange pushback of analytics in the NFL that is unseen in other leagues. The sentiment that “nerds don’t know football” is present and teams often look to hire “football people” rather than innovators. With all of that being said, there is still a noticeable evolution in the sport that we will uncover. Teams are passing the ball more and playing more aggressive than ever which presents a more exciting viewing experience.
It's a Quarterback League
Football is pretty different from “fluid” sports like basketball and hockey in that it has very well-defined plays. Each offensive down (besides special teams) you have the option to run or pass and those plays lead yards gained or lost, an outcome. Because these plays are so well defined, we are able to simply compare yardage gained on passes and yardage gained on runs to determine which play type is generally more efficient and how closely related they are in value.
From the chart above we can clearly see that passing is consistently more effective than rushing. In the 2019 season, teams gained 6.3 yards per pass and only 4.3 yards per rush. I mentioned before that this stat only gives us a general sense of efficiency. It does not account for interceptions thrown on passes and fumbles lost on rushes but it is worth mentioning that an interception is almost always less detrimental to an offense than a fumble while rushing because a passing turnover typically occurs down the field while a rushing turnover typically occurs near the line of scrimmage. This means that the opposing team usually has to overcome more yardage to score after an interception than a rushing fumble. The stat also fails to take into account penalty yardage. It should be noted however that penalties on pass plays typically favor the offense for what could be big chunks of yards on pass interference. Rushing penalties are usually called against the offense for holding, knocking them back 10 yards. The exclusion of penalties and turnovers from the stat both mean that the true imbalance in efficiency is actually even greater than what is depicted above. NFL decision making is greatly depending on the situation, i.e. clock management, down & distance, etc. so if passing is so much more valuable, when should teams ever rush the ball? First let’s look at how often teams are favoring passing to rushing.
Teams are slowly but surely starting to trust their passing game but this gradual change is nothing like the rapid evolution seen in the NBA. The pass-run ratio in 2019 was 1.33 which is an improvement but teams are still rushing way more than what is optimal. It seems that coaches are using first and second down to set up a killer third down play to move the chains when in reality, the best third down play is avoiding third down altogether. According to Football Outsiders, teams that pass on 1st & 10 score more points, earn more first downs, and punt less on drives than teams that opt to rush. They found that the only time that rushing yields more benefit than passing is on third down and three or less and in goal line situations. The yardage needed in these situations is low and the risk of an incompletion and gain of zero yards is pretty detrimental.
Running to Kill the Clock
We mentioned that when making play calling decisions coaches have to weigh the time on the clock with the down & distance. A potential benefit to running in favor of passing is that running the ball always keeps the game clock rolling whereas an incomplete pass stops the clock. This can be beneficial if a team is ahead and wants to drain the game clock and give their opponent less scoring chances. People often point to winning teams having a greater time of possession and thus are “controlling the clock” and cite stats like “The Titans are 13-2 when Derrick Henry (their running back) has 18 or more carries.”
In reality, winning teams are often hurting their chances by playing in an inefficient style when ahead. They abandon the play style that likely put them ahead in the first place and open the door for the opponent to get back in the game. Controlling the tempo in football just isn’t as important as many believe. As Arrowhead Pride points out, “no matter what kind (or how many) plays they run, both teams get an equal number of chances on offense.” In 2018, not a single team averaged a full drive more or less than their opponents. The team that maximizes their score every possession will win the football game. The correlation between time of possession and winning is not rooted in winning teams ‘controlling the clock better than their opponent.’ Time of possession is caused from having longer drives which typically indicates more points scored which obviously correlates with winning. Citing a team’s success when relating rushing volume to wins as a way to prove that rushing is as essential as passing is extremely misleading and outright dumb. Whether or not it’s smart, teams tend to rush more when ahead and conversely, teams all but abandon the rush when trailing especially late in games. Teams also win 100% of the time when the take a knee at the end of games. It would be foolish to use that stat as any sort of indicator that taking a knee leads to success. In fact it is the opposite; success leads to kneeling and the same is true of rushing the ball.
Why Running Backs Don’t Matter
Even with the running game being overutilized, various studies have shown that running backs themselves hold very little to no value at all. College, high school, and NFL coaches overuse and wear out their running backs and they usually hit their prime before they’re even eligible to sign a second contract. Ben Baldwin of The Athletic found that their “Yards over Expected” is extremely noisy year to year meaning that a running back’s skills in one season don’t necessarily predict their skills in the next.
Predicting which running back will have a “breakout year” and which will fall to injury or have a “unexpected” drop off is all but random. I put breakout year in quotes because a running back having a breakout year is far less valuable than most other positions having a breakout year.
Pro Football Focus stated that “a running back should never be MVP.” Their research found that the average “Wins Above Replacement” value for a running back getting a significant number of snaps is 0.1 meaning that their production accumulates to adding only a tenth of a win in a given season. This is less than that of more important offensive specialist positions like wide receiver, tight end, and especially quarterback. The last running back to win MVP was Adrian Peterson in 2012 when he posted a WAR of 0.30. Compare that to 2018 MVP Patrick Mahomes adding an estimated 4.39 Wins Above Replacement. In 2019, Carolina Panthers running back Christian McCaffrey received some MVP buzz after a record-breaking season. Despite putting up huge numbers, his position just doesn’t add much value; Carolina finished last in their division with a 5-11 record.
During the 2019-20 offseason, the NFL held a data modeling competition called the “Big Data Bowl” in which participants attempt to predict how many yards a rusher gains on a given play at the point when they are handed the ball. The winning entry found that “judging at the moment of the handoff, it is not statistically important who the ball carrier is. It is important what the situation on the field, driven by starting formations and movements of the players prior to handoff, including rusher’s movement.” This is huge. The winning model to predict how many yards will be earned on a given rushing play DIDN'T EVEN FACTOR IN THE RUSHER.
Despite all of this, teams still continue to draft running backs in the first round and give out huge second contracts to backs who may have had a breakout year.
Aggressiveness
The graph below depicts 4th Down Go attempts and two-point conversion attempts over the recent seasons. Teams are becoming slightly more aggressive year to year but the change isn’t too staggering yet.
Coaches still punt too much in situations where win probability models point to the offense staying on the field but the win probability lost on fourth down is slowly decreasing.
There is a huge disparity among teams with coaches like Pete Carroll of the Seahawks who like to punt the ball and “trust the defense” vs. coaches like John Harbaugh and the Ravens. The Ravens employ a ‘football analyst’ with direct communication with coach Harbaugh who will remind the coach about rules they set in the week of preparation about how aggressive they want to be in certain situations to maximize their win probability. The Seahawks employ no such individual.
Teams converted on fourth down 50.7% of the time in 2019 so expect teams to keep their kickers and punters on the sideline even more in the future. The notion that punting the ball is in any way “trusting your defense” doesn’t really make much sense. If you truly trusted your defense you would be okay with the fact that a failed fourth down conversion gives the opposition better field position than punting. If you trust your defense to get a quick stop regardless, then why not roll the dice with your offense on fourth down? I am not advocating to never punt the ball, but teams need to certainly stop punting when they are on their opponent’s side of the field and in scoring position, they should stop attempting long field goals with high degree of difficulty that produce only 3 points on a success, and they need to be more aggressive when trailing late in games. The win probability lost on fourth down is decreasing but there it still leaves much to be desired as far as making optimal decisions that should be driving fans nuts.
Wrapping Up the NFL
Overall, we found evidence that the NFL is making strides integrating analytics into their decision making processes but the league still has a lot of evolution left in store. I personally think this bodes very well for the NFL because I like seeing higher scoring games and teams being aggressive. In the future, expect to see offenses staying on the field more on fourth down and teams spending more capital on players that can offensively assist in the passing game and defensively take away the passing game.
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