Defense May Win Games, But Offense Wins The Game: A Data-Based Dive into Ivy League Football

“Defense wins championships” is an adage heard in many sports, including college football. But does it pertain to the Ivy League? As the historic Harvard-Yale descends upon the Crimson, what factors are crucial to the team’s success in the matchup –– and how might they differ from conference-wide play? We looked through the past five years of Ivy League football data to try and answer these questions.

The Ivy League

While defense is important, it’s no secret that a strong offense is a vital part of any football team — and the Ivy League is no exception. Specifically, rushing offense has played a pivotal role in the team’s success. Offensive-rushing-yards-gained was correlated with win percentage by a Pearson coefficient (PCC) of 0.56, the highest correlation among non-points-related metrics (for context: a PCC of 1 or -1 means that two variables are perfectly correlated, whereas as PCC of 0 denotes no correlation).

Meanwhile, passing the ball doesn’t hold much water among Ivy League champions. The total passing yards and win percentage were correlated by a PCC of 0.008, indicating almost no relation between teams with better passing offenses and teams with more wins.

Other significant tells of a team’s performance lay in their conversion of third and fourth downs. Teams who moved the markers in these crucial moments typically saw better records, with PCCs both of over 0.4. (Note that while performance on these high-pressure plays was significant, stronger teams had less need to convert third and fourth downs in the first place –– in fact, third and fourth down attempts were negatively correlated with win percentage, with PCCs of -0.44 and -0.36 respectively.)

On defense, stopping the run was another good indicator of a high win percentage. Teams who stopped the opposing team’s run effectively almost invariably ended up near the top of the league table, with a of -0.78. Meanwhile, passing yards and win percentage were correlated by a PCC of -0.3, much stronger than on the offensive side of the ball.

In terms of pure yardage, stopping yards on the whole was more indicative of team success than a high-octane offense. In rushing yards, passing yards, yards per play, and yards per game, absolute correlation to win percentage was higher on the defensive side of the ball for every metric.

So, does defense win Ivy League championships? These data suggest that while offense doesn’t hurt, good defense gets you a better bang for your buck.

Harvard-Yale

For many students and alumni, winning the Ivy League title may be important, but winning The Game is the first priority. What factors might contribute most to a Crimson or Bulldog victory on Saturday?

Harvard has a reputation for stifling the run, an attribute born out of the data.– Over the past five seasons, the Crimson has led the league twice in rushing yards allowed, never finishing lower than third. In the past five seasons, Yale has beaten Harvard only once in rushing yards allowed in 2017.

While the Bulldogs seem to stop the pass more effectively, at least in the past three seasons, the differences between the teams are minor –– yards-in-the-air-allowed by the two defenses since 2017 have never differed by more than 200 yards over a whole season. This comes in contrast to a wide discrepancy in rushing defensive performance. In 2018, Yale allowed over 500 more yards on the ground than Harvard, an average of over 50 yards per game.

The defensive performances of each team don’t seem to be a predictor of the outcome of The Game. While the Crimson is expected to stop the run and the Bulldogs are expected to stop the pass, neither attribute moves the needle much on game day.

The offense tells a different story in the Harvard-Yale game, particularly with regard to the run. In all five of their last matchups, the team with the more productive rushing offense ended up with the victory. The team with the most points scored over the full season also prevailed in all five games.

Not all offensive statistics have matched with Harvard-Yale outcomes. On third down, Harvard’s conversion percentage has trailed Yale’s every season since 2017. While the Crimson has been more aggressive than Yale on fourth down in four of the last five seasons, their aggressiveness hasn't precipitated higher efficiency –– the Bulldog’s fourth down conversion rate has been on average 13 percent better than Harvard’s over the five-year stretch.

Despite being a predictor of general Ivy League success, the defensive performance of Harvard and Yale over a full season predicts little about the results of The Game over the past five seasons. Meanwhile, the better rushing offense by volume has prevailed each time. While a solid defense may win more games overall, the Harvard-Yale matchup seems to be decided by the ability to score rather than stifle.

This Season

This Saturday, Harvard and Yale both seek to win the 139th edition of the rivalry matchup in the Yale Bowl. The Crimson comes to New Haven leading the Ivy League in rushing yards through nine games — 398 yards ahead of the second-place Bulldogs.

“It’s very important to us,” said offensive coordinator and wide receivers coach Mickey Fein. “That’s kind of where we start, is like, how can we run the ball?”

Harvard’s offense also leads Yale in fourth-down conversion rate, the first time in six seasons. It trails the Bulldogs in third-down efficiency, converting 46% of their attempts compared to Yale’s 49%, which leads the Ivy League.

“They’re good on offense and you want to stay on the field, doing that through conversions of third and fourth downs,” said Fein, emphasizing Harvard’s 12-for-19 third down performance against Penn last Saturday as momentum to build upon for the game ahead.

While Harvard’s pass offense has not been as productive as Yale’s, logging 319 fewer yards in the air over nine games, Fein valued the pass for the chunk plays it produces.

“It’s a lot easier to score the ball when you have a plus 20 play in your drive,” he noted.

On the other side of the ball, Harvard has maintained its stellar rushing defense, allowing 106 yards per game to the Bulldog’s 136. However, it enters The Game having given up the most passing yards in the league.

Harvard’s dominance over the Ivy League this season, paired with their prowess at stopping the run, falls in line with the already strong correlation between rushing defense and win percentage. If previous Harvard-Yale-specific trends continue, the rushing firepower behind the Crimson’s offense points to yet another victory on Saturday.

However, whatever the data might say, Harvard-Yale will be decided by performance, not by statistics. “It’s not a ton of…different things we’re gonna do or how it’s gonna all play out,” said Fein, referring to the team’s preparations for Saturday. “It’s more so just making sure the guys understand the task at hand.”