How Valuable Is Attempting a Fourth-Down Conversion?
When someone has everything to win and nothing to lose, nothing seems like too big of a gamble.
For the longest time, the safe play -- the expectation, even -- in football was that most fourth downs would see a team punt the ball away, no matter the distance to go. The logic was that a team would rather try to pin their opponents deep and make their offensive field longer, instead of taking a risk and trying to prolong their own offensive drive.
One high school football coach has challenged that convention in a very big way, however.
Kevin Kelley, head coach of Little Rock (Arkansas) Pulaski Academy’s football team has refused to punt simply for the sake of conventional wisdom. Kelley flipped the notion of punting on its head, asking -- if punting was never a part of football -- what fans would think if a coach sent out a new unit for the sole purpose of kicking the ball to the defense after three plays.
His ideas have even been backed up by university professors in scholarly articles.
We often take for granted these conventions of football, but sometimes these radical changes take advantage of drastic market inefficiencies in our beloved game. Whether it’s going for two after a touchdown, or attempting to keep a drive alive on fourth down, sometimes football needs to be shaken up.
Yet, what has worked in Arkansas high school football won’t necessarily work in the National Football League.
Just how valuable is attempting a fourth-down conversion in the pros?
Friday Night Lights
Here’s the premise to this seemingly ludicrous notion: Grantland made a short documentary about Kelley in 2013, where he explained that his Bruins tended to convert their fourth-down attempts around 50 percent of the time. He revealed that his team’s opponents tended to score around 92 percent of the time when the Bruins turned the ball over on downs the other 50 percent of the time.
When they punted -- on average to the 40-yard line -- they scored around 77 percent of the time. To Kelley, a punt’s 15 percent diminishment in the chances of their opponents scoring was heavily outweighed by the diminishment from the chances of the Bruins converting from 50 to 0 percent.
Seems reasonable, right?
But how do these notions translate to the NFL game? Fortunately for us, Pro Football Reference has a “Drive Finder” function that allows us to set parameters for the beginnings, middles, and ends of drives, so that we can test Kelley’s idea in NFL terms. Simply, what I did was pull all drives from 2015 that began in a punt and compared their results to drives that began in a turnover on downs.
The table below shows the outcome rates of each kind of drive in 2015. Is it better to turn the ball over on downs, or punt it away?
Sure enough, the data has it: punting is better odds to keep your opponents from scoring, and there’s no two ways about it. In fact, punting gives teams a 4.9 percent better chance to keep their opponent from scoring.
But that’s not the whole story.
Never Tell Me the Odds
Remember, even Kelley admitted that punting gave slightly better odds that the opposition wouldn’t score. He never argued that. What he argued was that it was such a marginal chance to prevent them (4.9 percent, as we saw) while reducing your chance of sustaining your drive to zero.
The compelling thing is that he was right about the odds: in the 2015 season in the NFL, 48.5 percent of fourth-down plays resulted in either a first down or a touchdown.
Even if we look at the dreaded “deep in their own territory” situation, the likelihood of a team’s opponent scoring from inside the 10 is 92.1 percent. If a team punts from inside the 10, their opponent's average drive begins at the 48-yard line.
Drives starting from between the 45-yard lines had a 62.9 percent chance of scoring last year. That 29.2 percent difference is still outweighed by the chance of making a fourth-down conversion (again, 48.5 percent).
Something interesting also emerged in the drive data: drives beginning on downs had an average score margin of +7.5 for the offense; drives beginning on a punt had an average score margin of +0.3. This means that the teams in the NFL who are attempting fourth-down conversions, on average, are a full score or more behind their opponents, and one score more than the average team that punts.
This just reinforces how much “going for it” on fourth down is seen as a desperation play in professional football.
It seems the NFL has the odds on this all wrong. But when we talk about probability and percentages, most NFL minds -- even fans -- turn off and tune out. What is the nitty-gritty on the value that punting is costing NFL teams?
Fourth and Wrong
Here at numberFire, we don’t just break down yards, scores, and turnovers to understand the game of football. We use a metric called Net Expected Points (NEP) to give context to the production that occurs on the field.
NEP helps us take the numbers we get from the box score and shows how a team or player performed versus expectation. By adding down-and-distance value, we can see just how much each play and each team, as a whole, influence the outcome of games. A 5-yard gain means more on 3rd-and-2 than it does on 3rd-and-10; it should be valued accordingly. For more info on NEP, check out our glossary.
By comparing the NEP value of an average NFL punt against that of a fourth-down conversion attempt, we can assess Kelley’s claim that punting is truly a loss.
To do this, I used numberFire’s play-by-play data and assessed every punt and fourth-down attempt in 2015 to see how much -- if any -- value was being lost by punting.
The table below shows the cost of the average punt and fourth-down attempt from this season. What pays off?
|4th Down Attempt||0.14|
The average of fourth-down conversion attempts produced more Net Expected Points this year than punting the ball away on fourth down. This is why teams “go for it” in crucial situations instead of hoping for the best and putting their fate in another team's hands. The numbers, this year at least, support Kelley’s theory, even in the pros.
Perhaps that’s why we saw more per-team fourth-down attempts with playoff lives on the line in the Wild Card Round (1.50) than we saw in the regular season (0.94). Perhaps that's why Seattle and Washington attempted a total of 7 fourth-down conversions with their season on the line -- they combined for just 22 across the regular season.
When teams play like they have nothing to lose on every play, like Pulaski Academy, they have the chance to gain everything. And their chances are pretty good.