ETH Expert Reviews Swiss Team Rivals

From 11 June, countless millions of people will be following the football World Cup in Canada, Mexico and the USA. They will discuss their team's performance, talk like experts about tactics and formations and cower behind the sofa during penalty shoot-outs. But a lot of what comes across as gut instinct and long-established football wisdom can now be verified with the help of data.

And this is exactly the kind of work being done by Ulrik Brandes, Professor of Social Networks at ETH Zurich. For many years now, he has been studying how to understand football using methods associated with network and data analysis. His research into the world's favourite pastime is even helping the Swiss national team to prepare themselves better for their opponents. "Football often appears to have an unpredictability and spontaneity about it," says Brandes. "But if you look at enough data, stable patterns start to emerge."

Tactical analyses for the Swiss national team

When the coaching staff for the national team are preparing for matches at the 2026 football World Cup, they try to understand how their opponents will actually play, going beyond the formations on paper. Besides traditional video analyses, this also involves using methods developed by Ulrik Brandes.

The ETH professor has been working with things like tracking data from international tournaments for several years. These days, most matches are filmed by several cameras, which record where every player and the ball are at any given second. Using this data, Brandes determines, for various game situations, how the players' positions change in relation to their team.

This provides a dynamic picture of tactical formations. In modern football, this dynamic view of how play unfolds makes a decisive difference, as players' positions are far more flexible than they used to be. They often switch roles, swap sides and behave differently depending on whether or not they have the ball. Static graphics of tactics, which we all know from countless half-time analyses, tend to fall short here.

Rapid visualisation of patterns of play

"Both before and during the World Cup, we will be using our methods to try to visualise tactical aspects and patterns of play that are not evident from the formation shown on television," says Brandes. For example, Brandes' analyses might reveal that the opponent's left-back is far more attacking than the right-back, a centre-forward tends to drop very deep, or which defensive midfielder acts as playmaker and might be vulnerable to pressing. All this allows the coaching staff for the Swiss national team to work out where the opponent's weaknesses and vulnerabilities might lie.

Brandes does, however, stress that he only prepares the data and does not make any tactical recommendations. Any decisions about what conclusions to draw from analyses are a matter for the national team's coaching staff alone. But particularly at a World Cup, where you hardly have time - after the group phase - to run the rule over all potential opponents using traditional video analyses, the analyses by the ETH researcher have the benefit of being deliverable much more quickly.

Why only three out of four penalties are scored during shoot-outs

But Brandes is not only concerned with studying the tactical patterns adopted by teams. He has a scientific interest in penalty shoot-outs too. These are regarded as the ultimate test of nerves and are often decisive moments in terms of trophies and careers - so the World Cup in Canada, the USA and Mexico will be the same.

But how do penalty shoot-outs actually differ from penalties during normal play? And is the often-heard piece of football wisdom - that teams who go first are at an advantage - actually true? Following an analysis of almost 2,000 penalty shoot-outs, Brandes and his co-authors were unable to confirm this. "The statistics contradict the claim that teams who go first are more likely to win," explains Brandes.

The same study also shows another clear finding: whereas roughly four out of five penalties are scored during normal play, only three out of four are scored during penalty shoot-outs. The key difference has nothing to do with goalkeepers: "The main thing we see is more misses. Even players who are otherwise very reliable score less often in penalty shoot-outs," says Brandes. It is clear that the additional pressure has a direct effect on the conversion rate.

How safe a 2:0 lead really is

At World Cups, it is not unusual for teams to take a 2:0 lead. That might feel comfortable. At the same time, commentators regularly warn that teams with a 2:0 lead are lulled into a false sense of security, which can jeopardise their chances of victory.

This is another piece of football wisdom that ETH Professor Ulrik Brandes has tackled. For one particular study, he looked at 100,000 matches from ten European leagues since 1990. The focus was not on the final score, but on the period immediately after the second goal.

The analysis found that teams do mostly go on to win after taking a 2:0 lead, but concede a goal more often than after taking a one-goal lead or after an equaliser. Particularly in the first twenty minutes after a team takes a 2:0 lead, the risk of conceding a goal, to reduce the lead to one, increases slightly.

"This doesn't mean that taking a 2:0 lead is bad, of course. But the dynamics of the game clearly change in some way, and this very period is more likely to see goals from the opposing team," explains Brandes. So to sum it all up, time-honoured football wisdom does have a kernel of truth - but quite a bit less than many people would have you believe.

Does football still have room for the unpredictable?

However comprehensive and complex today's data and analysis models might be, luck and chance remain decisive elements of the game. A deflection, a rash foul or a missed penalty can still mean the difference between victory and defeat.

"Data makes it easier to identify connections. It doesn't take the excitement out of football, but makes the beautiful game even more so," says Brandes. And this is why a World Cup is so fascinating. The sophisticated methods, like those used by the ETH professor, might well reveal important patterns of play and finer tactical points. But what ultimately happens remains unpredictable - until the final whistle is blown.