Does defense actually win championships?
Legendary football coach Paul "Bear" Bryant famously said, "Offense sells tickets. Defense wins championships."
The thinking goes that while offense may be flashy and exciting, solid defensive play - less noticeable, but more steady and predictable - forms the foundation of successful teams.
So is there any truth to the adage?
Reaffirmation - with a twist
In our study, we looked at football and basketball, taking different approaches for each sport. For football, we limited our sample size to teams that had made the NFL playoffs during the Super Bowl era, which gave us 515 playoff teams to analyze.
To represent a team's offensive ability, we used regular season yards gained per game; for defensive ability, we used the statistic of yards allowed per game. If defense wins championships, the teams that tend to allow the fewest yards over the course of a season should have the most playoff success.
What did the numbers say? After running some regression analyses, we found that defense, indeed, does win championships. The fewer regular season yards a team allowed in the regular season, the more playoff wins they tended to have.
So there you have it: Coach Bryant is a genius, and we should all head to Las Vegas to bet on the teams with the best defenses.
But as ESPN's Lee Corso would say - not so fast, my friend.
The same analysis revealed that yards gained offensively during the season correlated similarly - nearly identically, in fact - with subsequent playoff success. It turns out we should probably amend the adage to say: "Really good defense wins championships. And really good offense also wins championships."
This doesn't quite have the same ring to it, but it seems to be more reflective of the data.
In a similar analysis of 632 NBA playoff teams since 1971, we arrived at similar findings. Substituting the field goal percentage of teams' opponents for the yards gained by teams' opponents, we saw that regular season defense correlated with basketball playoff success. But regular season offense did, too - again, at a similar rate.
Playoff pressure doesn't discriminate
If you were to look at previous sport psychology research, you might have reason to believe that a good defense was more important than offense when it came to winning a championship.
Most studies of why athletes might either "choke" or be "clutch" under pressure had tested fine motor skills such as field goal kicking in football and free throw shooting in basketball. On the other hand, defensive skills typically require more footwork and continuous movement, and - in the case of a defensive lineman or a linebacker in football - physical strength.
For this reason, it was generally assumed that defensive play might be more stable, and less susceptible to pressure when seasons are on the line. If this were true, then the play of good defensive teams would remain steady during the playoffs, while good offensive teams would be more vulnerable to pressure-packed situations.
So what might explain why our findings suggest otherwise?
It may be that defensive players feel the pressure just as much as offensive players do, with their performance prone to the same fluctuations. After all, most burly defensive linemen aren't just blindly crashing into the line; rather, they're moving with the precision of a ballet dancer. At the very least, when it comes to dealing with pressure, it probably doesn't matter if you're a cornerback or a quarterback; sport psychology research has shown that athletes who feel confident and in control are more likely to give a clutch performance.
Incidentally, our NBA data suggested that three-point shooting may be the basketball skill most vulnerable to pressure - more than defensive skills. For basketball, then, a new hypothesis might be: "Clutch three-point shooting wins championships." In a previous study on baseball, we found that hitting ability may fluctuate more in the postseason than pitching ability. This implied that "clutch hitting wins championships."
Maybe we just haven't looked at football under the microscope carefully enough, and it's worth analyzing whether specific positions or actions - throwing a football, protecting the pocket, covering a wide receiver - are more vulnerable to pressure. Maybe "offensive line play wins championships," or "quarterbacking wins championships."
But for now, I'll make the bold prediction that the best defensive team will win Super Bowl 52 - that, or the one that's best at offense.
Mark Otten does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.