AFCON 2021: Eight interesting data points from the Group Stage

The AFCON 2021 Group Stage is over and it’s time to reflect on what’s happened in the tournament so far.

There have been some major upsets, with defending champions Algeria and favourites Ghana finishing last in their groups. Algeria came into the tournament with a 34-match unbeaten streak but has only managed to get a point in three games. 

On the opposite side, the two debutants (Comoros and The Gambia) have managed to qualify for the Round of 16 and dream of progressing further in the tournament. Another surprise has been Equatorial Guinea, who have finished second in their group in their first participation based on sports merit (they were the hosts in their previous two AFCONs). The Nzalang Nacional (representing the only Spanish-speaking country in Africa) have had an excellent tournament so far with a squad composed mostly of players from the Spanish lower leagues, a few of them with La Liga experience.

In this data analysis, we’ll look at some facts and data points that have caught our attention.

Expected goals and expected points

The first point of this data analysis will focus on how teams have performed compared to their expected goals (xG) and expected points (xP). We’ll have a look at some general tendencies and also at the outliers when comparing these statistics to the actual goals and points.

The first thing we note when looking at the xG in the AFCON 2021 Group Stage is that teams are underperforming them on average. The average xG in the three games played so far is 3.56 per team but the average goals scored is just 2.83. This means teams should have scored 25.8% more goals than they did. A mix of bad finishing and some incredible goalkeeping performances explains this data. 

It’s also interesting to note that the three teams with the lowest xG across the three group stage games have all qualified for the Round of 16. These teams are The Gambia (scored 3 goals from 1.55 xG), Malawi (scored 2 goals from 1.57 xG) and Comoros (scored 3 goals from 1.77 xG). On the opposite side, we find Guinea-Bissau, who have only scored 1 goal from 4.1 xG and finished last in their group.

Now let’s take a look at the expected points. As it’s normal over a short period like three games, xP don’t correlate very well to actual points in the AFCON so far. The graph below shows every team’s xP and points. The dotted line separates those teams that got more points than expected (right) and those who got less (left) and the colour shows the difference between points and expected points, with green being positive and red negative.

The blue line shows the correlation between xP and points and its slope is much lower than the dotted line, showing xP didn’t correlate very well with points. 

The eight teams that deserved to be out of the AFCON according to xP were Malawi, Sudan, The Gambia, Sierra Leone, Comoros, Ghana, Mauritania and Zimbabwe. Three of them (Malawi, The Gambia and Comoros) qualified for the next round while Algeria, Ethiopia and Guinea-Bissau were eliminated despite not being among the worst eight.