In their Freakonomics-for-sports book, “This is Your Brain on Sports,” Jon Wertheim and Sam Sommers uncover the hidden influences in sports and use reams of data to investigate questions that tug at every fan. Why are quarterbacks so good-looking (or are they)? Why do we love the underdog? What’s the appeal of the stupid T-shirt cannon?

In the following adapted extract, the authors – one a sports journalist, the other a psychology professor – consider whether defense truly wins championships.

Super Bowl 50 will feature this season’s presumptive MVP, Cam Newton, against five-time MVP Peyton Manning. It will feature a veritable NFL start-up – the Carolina Panthers, a team with no Super Bowl wins and a losing record for the franchise’s history – against the Denver Broncos, the NFL equivalent of a blue chip. It will also feature the league’s sixth-best defensive team and the best defensive team this season.

On this last point, casual fans might have suspected as much. Why? Because defense wins championships. Coaches of all levels and sports have said so for years. This isn’t even a locker room cliché. It’s hardened into one of the organizing principles of team sports.

Except that it ain’t necessarily so. What we found: when it comes to winning championships – or winning in general, for that matter – defense and offense carry uncannily similar weight. Among the 49 NFL Super Bowls, the better defensive team, measured by points allowed that season, has won 30 times. The better offensive team has won 25 times. It’s a slight edge to defense, but it’s a pretty close call, and not different from random chance. The Super Bowl champ has been a top-five defensive team during the regular season on 31 occasions. How many times was the Super Bowl champ ranked among the top five in offense? 27. Damn near even.

But we’re talking about only 49 games, so let’s broaden the sample size. There have been 462 NFL playoff games held over the last 49 seasons. The better defensive teams have won 58 percent of the time. The better offensive teams have won 62 percent of the time. Slight edge to the offense, but, again, pretty even. (Sometimes the winning team is better both offensively and defensively, which explains why the total exceeds 100 percent.)

Collectively, teams with a top-five defense have won 180 playoff games. Teams with a top-five offense have won 184 games. Accounting for almost 10,000 regular season games, the better defensive team has won 66.5 percent of the time compared to 67.4 percent of the time for the better offensive team. Again, a negligible difference.

What happens when the best offenses line up against the best defenses, if, say, the 2006 Indianapolis Colts had had to face the 2000 Baltimore Ravens? It turns out that 27 Super Bowls have pitted a top-five offense against a top-five defense. The best offensive team won 13 and the best defensive team 14. Another virtual stalemate.

Same, incidentally, in other sports. Of the 69 NBA championships from 1947 to 2015, the league’s best defensive teams during the regular season have won ten titles – including the Warriors last year – while the best offensive teams have won seven. In the playoffs, the better defensive teams win 54.4 percent of the time, while the better offensive teams win 54.7 percent of the time – almost dead even. And among more than 55,000 regular season games, the better defensive teams win no more often than the better offensive teams. We see the same results in the NHL. There’s no greater concentration of Stanley Cups, playoff wins, or regular season victories among the teams playing the best defense (or defence) than among those playing the best offense.

If defense is no more critical than offense is, why do all youth coaches worth their polyester shorts extol its singular importance? Well, no one needs to talk up the virtues of scoring. No one needs to create incentives for players to shoot more jump shots or score more touchdowns. There’s a reason why fans exhort “De-fense, De-fense!” not “Off-ense, Off-ense!” Offense is fun. Offense is glamorous. Defense? It’s often less fun and, certainly, less glamorous, less glorified. Who gets the endorsements, the scorers or the defensive stoppers? And it’s not just sports. Think about war movies. The heroes, inevitably, are conquerors of territory, not defenders of territory. Acquiring something is inherently sexier than simply maintaining it.

But we submit that there is something else at play. The fear of loss is a huge motivator, both in life and in sports. Psychologists Daniel Kahneman and Amos Tversky are credited with recognizing this phenomenon, which they called “loss aversion.”

Distilled to its essence: we often tend to prefer avoiding losses even at the expense of acquiring gains. For most of us, the pain of losing $1 is far more intense and powerful than the pleasure of winning $1.

In a famous psychology experiment, subjects are offered two gambles with identical payoffs, but framed differently. In the first gamble, a coin is flipped and if it lands heads you get $100; if tails, you get nothing. In the second gamble you are given $100 first and then flip the coin; if the coin lands heads you owe nothing; if it’s tails, you pay back the $100. Subjects dislike the second experiment much more than the first even though the actual gains and losses are identical.

What about football? On offense, athletes seek a gain. They’re looking to score, to augment a total, to change the numbers on the scoreboard. On defense, athletes are simply trying to prevent points, to preserve the score and keep it from changing. On defense, the strong motivating forces of loss aversion aren’t really being activated. Nothing is at risk of being taken away or reduced.

We suspect that if sports were structured differently, defense might be perceived differently. Imagine if every game started not at 0-0 but with a score of, say, 25-25, and teams could have points deducted from that total. It stands to reason that the principles of loss aversion might kick in and inspire better defense to protect those points.

But until then, defense is no more important than offense. If you’re prognosticating the Super Bowl winner, there are certainly better metrics than simply siding with the better defensive team. It’s not defense that wins championships. In virtually every sport, you need either a stellar offense or a stellar defense. And having both is even better.

This is Your Brain on Sports is published by Crown Archetype, $26. Click here to buy it for $16.99.