Why NFL coaches should be more aggressive on fourth down

The Analytics Hero of the NFL’s opening week very easily could have been a goat. Late in the third quarter on an afternoon full of hope in Cincinnati, the Bengals faced a 4th-and-1 from their own 30, leading 21-7. And Zac Taylor, their 38-year-old head coach, faced a decision that 10 years ago would have been a no-brainer. Any rational coach would have punted. No sensible fan or pundit would have questioned him.

But Taylor coaches in the 2021 NFL, a league that is, slowly but surely, being remodeled by nerds. So he didn’t punt. He went for it. The decision, on top of being “gutsy” and “ballsy,” as his players said, was mathematically sound. It actually backfired, but mirrored similar decisions that . And it was emblematic of a changing league.

NFL teams went for 4th-down conversions 51 times this past weekend, the highest single-week total in modern league history, up from 37 in Week 1 last year, 26 in 2019, and 22 in 2018. That year, in Week 1, teams went on 4th down eight times prior to the fourth quarter. Just three years later, that number ballooned to 33.

And while circumstantial factors could explain some of the uptick, advanced statistical models show a significant trend. , a data analytics company that works with NFL teams, studies 4th-down decision making and the effect that each choice has on a team’s win probability. It analyzed every relevant and non-obvious 4th-down decision from Week 1 this year and last. It found that, cumulatively, suboptimal decisions on last season’s opening weekend cost teams a cumulative 170 percentage points of win probability.

This past weekend, that cumulative cost was only 104 percentage points — almost equal to the win probability gained from 4th-down aggressiveness.

In situations where viewed the go-or-kick decision as a “toss-up,” offenses stayed on the field 30% of the time, up from just 14% last year.

Analytics have long suggested that NFL coaches, a notoriously risk-averse species, should take more risks on 4th down. Gradually, as PhDs infiltrated football departments, coaches began to listen. The opening week of the 2021 season presented the clearest evidence yet that the nerds’ recommendations are taking hold — and, in some cases, helping win games.

CINCINNATI, OHIO - SEPTEMBER 12: Joe Burrow #9 of the Cincinnati Bengals jogs off the field after beating the Minnesota Vikings 27-24 in overtime of the Cincinnati Bengals against the Minnesota Vikings at Paul Brown Stadium on September 12, 2021 in Cincinnati, Ohio. (Photo by Andy Lyons/Getty Images)

The Bengals didn’t shy away from going for it on fourth down and, in the end, were rewarded with a victory. (Andy Lyons/Getty Images)

Reward outweighs the risk

Fourth-down aggressiveness doesn’t always snatch headlines. When it does, the headlines often highlight decisive plays or failure. But the best examples are usually buried deeper in games, and they were plentiful this past weekend. Sean Payton’s Saints, for example, went on 4th down twice on the same first-half drive. . Jameis Winston converted twice, the second time for a touchdown that accelerated .

In New York, meanwhile, Vic Fangio’s Broncos , drove for a chip-shot field goal, and never looked back.

In Vegas and Kansas City, the Ravens and Browns both jumped out to early leads thanks to . Kevin Stefanski’s Browns passed up field goals on each of their first two drives, converted on 4th-and-3 and 4th-and-1, , and .

The optimal decision, of course, does not always produce optimal results, and Bengals fans very nearly re-learned that the hard way. Taylor’s choice to go on 4th down from his own 30 increased the Bengals’ win probability by nearly 2 percentage points, . Their subsequent turnover on downs, obviously, did not. Less than a minute later, the Vikings scored and halved the lead. Eventually, they sent the game to overtime.

But Taylor didn’t regret his choice. “I don’t take back any decisions,” he later said. This was the correct one, just like his earlier decision to go on 4th-and-1 in field goal range. Joe Burrow got that first down, and three plays later, Joe Mixon got a touchdown.

So Taylor wasn’t fazed when, in overtime, his offense faced yet another 4th-and-1 in their own territory. Mathematical models said it was a “.” The Bengals indeed went, and .

The moral of the story is not that aggressiveness guarantees success. Several teams — the , , , , , and — made sound 4th-down decisions and came up short. The statistically supported lesson, instead, is that sound processes yield positive results more often than not. And coaches, finally, seem to be taking that to heart.

TAMPA, FLORIDA - SEPTEMBER 09: Head coach Mike McCarthy of the Dallas Cowboys looks on during the fourth quarter against the Tampa Bay Buccaneers at Raymond James Stadium on September 09, 2021 in Tampa, Florida. (Photo by Julio Aguilar/Getty Images)

Mike McCarthy’s decision to kick a field goal late in the the Cowboys’ loss to the Buccaneers was deemed the worst decision of Week 1. (Julio Aguilar/Getty Images)

The worst coaching decision of Week 1

They still, however, have a long way to go. From Week 1 alone, EdjSports unearthed 75 4th-down decisions that they characterized as “suboptimal.” Many of the 75, in reality, were toss-ups; the difference between kicking and going for it was, in some cases, fractions of a percentage point in win probability. Major errors were far more scarce than in Week 1 of last year, and perhaps more scarce than ever before.

But still, the cumulative cost of those 75 decisions was significant. And the vast majority of the mistakes were conservative ones.

Perhaps the most notable was one that very few seasoned football watchers questioned. On Thursday night, Dak Prescott expertly engineered a late-fourth-quarter drive, and set up Greg Zuerlein for what many assumed would be a game-winning field goal. But on 4th-and-6 from the Tampa Bay 30, with 1:29 remaining, down two points, EdjSports’ model and betting markets alike recommended that the Cowboys keep their offense on the field. Their reasoning, in short, was the likelihood of .

. Even after Zuerlein drilled a 48-yarder — which, of course, was no sure thing — the Cowboys were still more likely to lose the game than win it. Tom Brady with the ball, a timeout, a one-point deficit and 1:24 on the clock was still the betting favorite. By going for it, the Cowboys could have taken the game out of Brady’s hands. A conversion could have made Zuerlein’s field goal attempt both easier and decisive.

EdjSports’ model calculated all of this in real time. Retrospectively, it dubbed Mike McCarthy’s choice to kick the .

There were other maddening ones, too. The . The Falcons kicked on 4th-and-goal from the 3, and, 55 minutes later, realized it was one of their best and only shots at a touchdown. They finished the game with six points.

But perhaps the most dangerous decision was Matt Nagy’s to punt on 4th-and-2 with his Bears in Rams territory. Because it reeked of recency bias, or an inverse version of the “gambler’s fallacy,” or what one source described as “regret bias.”

The Bears had tried, correctly, to convert two 4th downs in the first quarter of their season opener. They’d failed, and Nagy seemingly let those failures cloud his consideration of the third situation, which was a clear “go.” And that cognitive bias is the only thing that could halt this rising tide of aggressiveness across the NFL. Coaches have, for decades, have made detrimental decisions on 4th down because they were afraid to fail. Whereas successful 4th-down conversions are often attributed to the players who executed them, failures are pinned on coaches and weigh them down.

The worry, then, is that coaches could regress as the season wears on, and that’s why experts will wait, patiently, for the sample size to grow before dubbing 2021 a 4th-down breakthrough. But past seasons suggest that aggressiveness will not wane as the season progresses. And the mathematicians behind the trend certainly won’t recommend fewer risks. They’ll recommend more.

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