# 2-0 is a dangerous lead? Data says no

An analysis of over 2’000 matches shows that the frequently used phrase “2-0 lead is the worst lead” is indeed just a bad cliché. There is only one lead in football that is really dangerous.

Football is full of coin phrases and clichés, but probably the most persistent is the misguided thought that a 2-0 lead of a team actually increases the danger of receiving a goal.

The cliché is so widly known that it actually got its own Wikipedia entry. Apparently, television commentator Josef Csaplár from Czechia populalrized it first. The assumption that the leading team feels a false sense of security when 2-0 up is known in Czechia as Csaplár’s trap. Since then, it has spread like wildfire, being used by football pundits, coaches and players all the time.

High time to debunk the cliché, once and for all.

Swiss Football Data analyzed over 2’000 matches of Swiss Football League since season 2010/11 to get to the bottom of this.

The approach is simple. The halftime result of the matches is getting compared with the final result. First, let’s take a look at the distribution of the dataset:

The chart shows the goal difference at halftime from the perspective of the home team. The most frequent scenario is a one goal difference: In 470 matches the home team did lead, 401 the away team had the edge. In 810 of the 2030 matches no team had an advantage at halftime.

In 282 matches, a team did lead by 2 goals (171 home team/111 away team). That is almost 14% of the overall sample and more than enough to determine any unusual pattern.

First, let’s look at how the winning odds are changing based on the halftime result:

As you can see, the increase of the winning odds is quite steady. With lagging 2 goals after the first half, the odds for your team to manage the turnaround are only a bit above 1%. If your team trails your opponent only by one goal, it takes the win in only 1 of every 10 matches (10%).

With a draw at halftime, the odds for a win increase another 20% to 31%, which means the team wins 1 in 3 matches. If your team leads by one goal, the chances for a win are at 67%. So only in 1 of 3 matches, the team will not leave the pitch as a winner.

## 2 goal lead increases the odds of winning considerably

Now to the juicy stuff. As expected, leading 2-0 at halftime increases the odds of winning considerably. Now, your team will end up as a winner in more than 9 of 10 matches. Compared to an one goal lead, the winning odds improved another 24 percentage points. Does that sound dangerous to you?

Let’s look at it from another angle. This time, we are asking the question: What can the halftime result tell us about the outcome of a match? The following table shows the average change of the goal difference.

Overall, the goal difference is more likely to get worse if your team is already trailing at halftime. This does not come as a surprise, since the halftime result is a pretty good indicator of the power balance on the pitch.

This analysis completely debunks the cliché of the 2-0 lead. If your team leads with 2 goals, it’s actually more likely that the lead will have increased at the end of the game. This is more true for home teams, but even away teams have a positive net gain. So a 2-0 lead is not only not dangerous at all, it also indicates further glory.

## A narrow lead away can be dangerous

An interesting pattern can be found with a one goal lead at halftime. With home teams, it’s more likely that they will increase the lead till the end. But when we look at the away team, it’s actually a bit more likely that the team loses the lead than increases it.

Bottom line: the only lead that can actually be considered dangerous is a one goal lead from the away team.

Take that, football pundits.