Intro
The UEFA Champions League, Europa League and Conference League group stages are about to begin this week so with the help of Opta’s Power Rankings, I decided to visualize the competitions from this perspective. This is a limited descriptive exercise and purely easy excuse for a simple new post.
“Opta’s Power Rankings is a global team ranking system that assigns an ability score over 13,000 domestic football teams on a scale between zero and 100, where zero is the worst-ranked team in the world and 100 is the best team in the world.” - The Opta Analyst
For additional details regarding Opta’s model see Introducing Power Rankings: Your Club Ranked.
The data
The data was obtained from Opta’s club ratings page on September 18th 2023. Ratings fluctuate with time and the below figures are the ratings retrieved at the time indicated which represents the moment before the start of the group stage of the competitions.
Visualizations
The following packages were used to produce the figures in R:ggplot2tidyverseshowtextggtextggiraph
(Gohel & Skintzos, 2022; Qiu & details., 2022; Wickham, 2016; Wickham et al., 2019; Wilke & Wiernik, 2022).
For Figure 2, 3 and 4, ratings were transformed into z scores (Equation 1) for added ease of interpretation.
\[ Z = \frac{{X – \mu}}{{\sigma}} \tag{1}\]