Jerraud Powers says that when the Colts drafted him at the height of the Peyton Manning–Tom Brady wars, he learned there were two goals: win the division and beat the New England Patriots. The Colts selected Powers from Auburn in 2009, and seven months later, the cornerback was lined up across from Wes Welker in one of the most heated chapters in what he says was the “best rivalry in football” at the time.

In the fourth quarter, as the two-minute warning was approaching, the Patriots faced a third-and-2 while holding on to a 34-28 lead. Powers knew based on his coverage that Welker would break toward the outside of the field and that he simply had to stay close enough to him to make a play on the ball. This was not a particularly easy task. “People forget how good Wes Welker was in that system,” Powers says. He stayed with Welker well enough to swat the ball away, and he was so close, he thought he might intercept the pass. Ten years later, he still wonders what his legacy would be if he had. But it was a key third-down stop, and Powers sprinted a few yards in celebration. “We knew the Patriots would punt and try to bank on their defense because they had a pretty good one that year,” Powers tells me.

“We ran off the field,” Colts safety Melvin Bullitt says. “We knew they were punting.”

“And then,” Powers says, “Tom Brady stopped jogging off the field and turned around.”

This week marks the 10th anniversary of that game, and more importantly, the 10th anniversary of what happened on the play after that third down: Backed up on their own 28-yard line, the Patriots went for it on fourth down. The greatest coach in the history of football, Bill Belichick, was making what most of the football world considered to be a monumental gamble. The NFL is still a risk-averse league, but prior eras of football were even more resistant. In 1995, when Cowboys coach Barry Switzer called a similarly bold fourth-down play from inside his own 30 and failed, it was accompanied by, among other headlines: “Switzercide,” “Fourth-and-Dumb,” and “Bozo the Coach.” By 2009, conventional wisdom among media and coaches hadn’t changed all that much. In fact, going for it was rarely discussed. Belichick did not invent going for it on fourth down. He was just coaching one of the biggest regular-season games of the decade, in prime time, in a game featuring two of the best quarterbacks of all time. In the decade since, attitudes from NFL coaches, executives, and media members have shifted dramatically about fourth down.

According to Michael Lopez, the NFL’s director of football data and analytics, through the first nine weeks this season, teams have gone for it on fourth-and-2 35 percent of the time and 53 percent of the time on fourth-and-1. In 2018, teams went for it on 24 percent of their fourth-and-2s during the same span. Sixteen years prior, teams went for it on fourth-and-2 only 16 percent of the time. This season, teams are going for it on fourth-and-2 about twice as often as they did in 2008, the year before Belichick’s 2009 gamble. This is not to say NFL coaches are ready to cut their punters—it’s still a deeply conservative league—but the change, however gradual, is undeniable.

“Whoa, they are trying to finish us now,” Bullitt remembers thinking.

Bullitt, a former undrafted free agent from Texas A&M, had made the Colts two years earlier after a strong mini-camp and worked his way into the starting lineup while the team’s star safety, Bob Sanders, battled injuries in the 2008 and 2009 seasons. In the week leading up to the game, Colts coaches told the defense that in short-yardage situations like the fourth-and-2 Bullitt was about to face, Brady would go to Welker or running back Kevin Faulk, who, Powers says, “was probably the best passing back in the league.”

A broad, national conversation about fourth down did not seem like it was going to happen any time soon in those days. The attitudes around fourth down hadn’t yet shifted as Brady took the snap. And, if you listen to some people in the NFL, they started to shift partly because Brady took the snap. When Faulk motioned toward Bullitt’s side of the field, he knew what was coming next. “I knew it was going to be short, and it was going to be quick. I knew it was my man, and I just had to react,” Bullitt says.

This type of aggressiveness in the tradition-bound NFL, of course, was rare at the time. Many thought the Patriots were trying to draw the Colts offside. After the snap, NBC announcer Al Michaels proclaimed, “And they really do go for it.” (For their part, the Colts knew the Patriots were running a play.)

“When I hit Kevin Faulk, my head was turned, and I could see the first-down marker. I was really confident that it wasn’t a first down,” Bullitt says. “It was a great call, and at the same time, it was just a great play by me to keep my feet moving.”

Faulk appeared to make it at first glance, but he was bobbling the ball, which cost him his forward progress, and Bullitt’s tackle stopped him short of the first-down marker. “Initially, everyone thought that [he made it],” Powers says. “When they showed the replay on the Jumbotron, that’s when we all went crazy, because you could see him bobble the ball. That’s when we went nuts.”

“That play definitely precipitated a lot of attention on analytics that never existed before.” —Brian Burke

The Colts took over on downs, and Manning drove down the field, hitting wide receiver Reggie Wayne for the game-winning score with 16 seconds left to give the Colts a 35-34 win. The reaction to Belichick’s decision after the game was merciless: “The worst coaching decision I have ever seen Bill Belichick make,” former Patriots safety Rodney Harrison said on NBC. For ESPN, former Patriots linebacker Tedy Bruschi said, “As a former defender on that team, I would’ve cared less about the result of that fourth-down attempt. The decision to go for it would be enough to make my blood boil for weeks.” And this was just among former Patriots. Belichick’s status as perhaps the smartest person ever to roam an NFL sideline spared him from receiving the same insults that were hurled at Switzer, but ultimately Belichick had bucked conventional wisdom so much that he pissed the football world off.

Watching the game from home that night was Brian Burke, a U.S. government contractor who also ran a football analytics website as a hobby and wrote analytics pieces for The New York Times. He was focused on a play that took place earlier in the day: Jaguars running back Maurice Jones-Drew took a knee on the 1-yard line instead of scoring to run the clock out in a game against the Jets. Burke joked that Jones-Drew’s play had been the “analytics play of the decade.”

“And then, the fourth-and-2 thing just exploded,” says Burke, who is now the senior analytics specialist for ESPN. “That was my 15 minutes of fame.”

Burke was busy writing a piece explaining Jones-Drew’s savvy move, but he quickly wrote up a four-paragraph defense of going for it on fourth down. The Times asked whether it could carry the piece, and it ran in the print edition and online. “Statistically, the better decision would be to go for it, and by a good amount,” Burke wrote. Burke says that the play would be successful 60 percent of the time, which would have ended the game. He pointed out that the Colts, with Manning, had a better-than-most shot of scoring from anywhere if they got the ball back in any capacity.

Burke’s life became quite busy: “My phone was blowing up. Peter King called me. There were a lot of articles. ESPN did a news-magazine-type story on TV. NFL Countdown had me and [Cal professor] David Romer on Sunday. Yahoo wrote this big article. I had to take a few days off work to answer all that mail.” Monday Night Football discussed Burke’s research in its pregame show. The Wall Street Journal dove in.

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What was happening was simple: The mainstream sports press was, for the first time, discussing the benefits of going for it on fourth down. Burke thinks that if Belichick had converted the fourth down, the play would have been quickly forgotten. But he didn’t, and the debate lasted weeks. The benefits of going for it on fourth down were known in the analytics community but were sparsely discussed inside NFL facilities or on television. Burke had developed a win-probability model that guided teams on when to go for it on fourth down that incorporated time and field position. In the spring of 2010, teams started asking him to consult on decision-making analytics. “I thought eventually teams would catch on. I knew the numbers, and I thought that eventually a smart team would revolutionize football. It happened a lot quicker than I thought,” Burke says. “That play definitely precipitated a lot of attention on analytics that never existed before.”

The math took a while to take hold: Teams did not immediately increase their fourth-down attempts after 2009. Instead, Belichick’s decision simply started a conversation—a more aggressive approach didn’t become commonplace until later in this decade. (Burke points out that the Patriots still don’t go for it as much as they should.) Burke calculates how conservative the league is on fourth down by a metric he calls “win probability forfeited,” which shows how often teams cost themselves an edge in the game by needlessly punting. NFL teams are forfeiting about half of what they did a decade ago, Burke says. To translate that, teams are suffering the consequences of bad decisions half as much as they did 10 years ago, so they are learning. The league changed dramatically—and there’s still a lot more room to go. In short, fourth down is increasingly an offensive down.

“In the 10 years since that play, I’ve had about 20 NFL people reach out,” says Kevin Kelley, head coach at Arkansas’s Pulaski Academy, who gained fame for forgoing punting completely. “I think Bill Belichick is the best coach in the world. If somebody ultra-successful does something, even if it doesn’t work, everyone takes notice and starts to evaluate it. I hate to say it, but if the Jets had done it at that time, it’s not a story, and we’re certainly not talking about it 10 years later. If the guru of all gurus does it, everyone takes notice.”

Fourth down can be a scary proposition for coaches. Even if there’s greater acceptance about being more aggressive, the math says to go for it so often—in so many precarious positions—that it takes a big adjustment to embrace the math. The New York Times’ Fourth Down Bot (which utilized Burke’s models) offers these rules of thumb for sound decisions:

On fourth-and-1, go for it any place on the field where that is possible, starting at your 9-yard line. On fourth-and-2, go for it everywhere beyond your 28-yard line. On fourth-and-3, go for it almost everywhere beyond your 40.

This, of course, is far too aggressive for NFL coaches (Ron Rivera told me the Fourth Down Bot got him more interested in going for it more often, but he has not come close to following its rules).

“I got this sheet yesterday that shows what you should do,” Packers coach Matt LaFleur tells me in a golf cart at Green Bay’s training camp before the season. “Analytics tell you to go for it whether you are on the minus-10-yard line, go for it on fourth-and-1. The average on fourth down is about 75 percent, so is it worth it to go for it all the time? You have to think about who you are playing, how you are playing. It’s not a black-and-white answer, I don’t care what anyone says. If we get to that midfield mark, yeah, I am way more apt to go for it. I am a little more reserved if we’re on the minus-10-yard line—three out of four times you get it, but when you don’t, that’s automatic points.”

LaFleur continues, saying fourth down depends on so many factors: Who is the opposing quarterback? What kind of game is it? What’s the weather? “I don’t think you can ever make it a blanket rule at all,” he says.

The Packers have gone for it a league-low three times this season, but of course, LaFleur has Green Bay at 8-2, and in strong contention for an NFC playoff bye, so he’s doing something right. His views are similar to how a lot of coaches around the league think about fourth down. There is, to be clear, no coach who is ready to embrace the analytics so wholly that they’ll regularly go for it on their own side of the field. The fear of handing a team points keeps coaches up at night. “I’m not going to go for it if it’s automatic points for the other team,” Browns head coach Freddie Kitchens tells me.

Most coaches I’ve spoken with are open to approaching fourth down as an offensive down, but they aren’t exactly ready to run Pulaski’s no-punt system. “In Week 12, you may love your short-yardage matchups, and in Week 13, you might not,” Vikings offensive coordinator Kevin Stefanski says. “So what’s important is constantly having those discussions during the week, so when it comes to game time, you have a pretty good feel for what you want to do. You’ve seen the trend go upward, and coach [Doug] Pederson got a lot of credit for how aggressive they were.”

“You have to think about who you are playing, how you are playing. It’s not a black-and-white answer, I don’t care what anyone says.” —Matt LaFleur

Pederson, of course, is the most notable recent exemplar of aggressiveness. In 2017, his Eagles team broke the NFL record for fourth-down attempts in a season on their way to a Super Bowl win, most famously converting the “Philly Special,” which went a long way toward defeating Belichick and the Patriots. “The bottom line is, I trust my guys. It’s going to be calculated,” Pederson said last year when I asked him about his approach on fourth down. Those “guys” are a part of another piece of this puzzle: Multiple teams now have an analyst advising coaches when to go for it on fourth down or for two-point conversions. Burke says if there is a second momentous event in the narrative of fourth downs in pro football, it is the Eagles’ 2017 campaign.

Of course, the Philly Special is significant because the Eagles converted in a Super Bowl, and the most conservative coaches won’t be swayed until conversion rates rise. Three teams—the Chargers, Saints, and Chiefs—had conversion rates in 2018 above 80 percent, a testament to their quarterbacks and short-yardage offenses. This does not mean all teams that frequently go for it on fourth down are smart: The Giants, for instance, have attempted more fourth downs than any team in the league this season (7-of-19) because they are so often losing. The Bengals are 7-for-17. Even longtime aggressive teams with talent aren’t guaranteed success: The Eagles—long the kings of fourth down—are 6-for-17. The Ravens are the only team over 75 percent so far.

Burke points to Ravens coach John Harbaugh’s press conferences as an example of how much the sport has changed. It’s not just that Harbaugh is open about his approach, Burke says, but also the fact that now media and fans understand the data as well. “The math is already done,” Harbaugh said last season. “We study all of that. We have all those numbers. That’s given to me during the game.”

The Ravens have gone for it 13 times this season, tied for fifth in the league. Ravens quarterback Lamar Jackson famously talked Harbaugh into one of those fourth-down attempts—a touchdown run against the Seahawks last month. “Baltimore, it’s amazing, they’ll go for it on fourth-and-short inside their own side of the field, and people don’t bat an eye anymore,” Burke says. He joked: “Ten years ago people would have taken out ads in the newspaper saying ‘Fire the coach.’”

Falcons general manager Thomas Dimitroff tells me he thinks the league has become more aggressive because of the focus on youth in the coaching ranks. “I have tremendous respect—and I don’t want to be accused of using an X Games phrase—for going for it or going home,” Dimitroff tells me. “That’s where we are now, and it’s only getting more so.”

What is the future of fourth down? That depends on whom you ask. Kelley, the Arkansas high school coach famous for eliminating punting, says NFL teams are still far too conservative. Part of that is coaches still being afraid of criticism, which he says is changing. “Think about the manager of the Texas Rangers. You don’t know what the guy looks like,” Kelley says. “But everyone knows the coach of the Dallas Cowboys. We all say the media doesn’t affect us, but if the media shines a light on us and says ‘You are all dumb-butts for not going for it,’ you can’t help but let that get to you.

“If there was a billion-dollar pharmaceutical company or a phone company like Apple, and they didn’t use the best numbers they were given, it wouldn’t be fine. In the NFL, guys make decisions that cost them 2 percent here, 3 percent there, and [it is considered] fine.”

Burke says that among the teams he’s consulted for, ownership is usually pushing for analytics, even if the coaching staff is hesitant. Owners are, after all, usually billionaires who have dealt with a lot of math in their business career and want to use it in football, too. It empowers coaches to take more risks if the call comes from the top. We saw this play out on another analytics-based decision on Sunday: Carolina coach Ron Rivera—whose boss, Panthers owner David Tepper, is fascinated by analytics—went for two instead of kicking the extra point after a touchdown and put his team down 24-16 to the Packers. He said his decision was “purely analytics.”

Fourth down will likely be impacted by technology. New NFL tracking data on the difference in short-yardage situations is more easily distributed. According to the Wall Street Journal, teams going for it on fourth-and-inches convert 82 percent of the time over the past two seasons. Long fourth-and-1s are converted just 55 percent of the time. Learning more about the different types of fourth downs will only arm teams with more information.

“As the analytic world becomes more and more a part of it, you’d be foolish not to do your research,” Bills offensive coordinator Brian Daboll says. “But there’s a feel to it. Numbers don’t lie—I also think there are factors like playing conditions, opponent, how the head coach envisions the game plan.”

I asked Daboll whether increased aggressiveness on fourth down would lead to teams focusing more on short-yardage plays. It’s sort of a chicken-and-egg situation, he explains. Most fourth-down attempts are not planned out. “I think it changes if you know what you’re doing ahead of time,” Daboll says. “There are so many factors, but if you have a feel for [going on fourth] that could change your third-down call.” Or, he says, “it could just be third-and-10, and you have no idea you’re going to get 9 yards.”

The Colts-Patriots game on November 15, 2009, is remembered as one of the best regular-season games in history. The Colts got to the Super Bowl that year and lost (they were 1-for-2 on fourth-down conversions).

I ask Powers what he thought of Belichick’s decision, knowing what we know now about the league. “It opened the box for coaches,” he says. “To believe in their guys that they can get a fourth-and-short. If you can do it, you should do it.”