Indicator xD (Determination for scorers)
4 min readJul 15, 2021
Do you want to know why Messi is more decisive than Cristiano Ronaldo? Here you will find out.
What is xD?
In short, xD is a coefficient (NOT a probability) that reflects the determination of each goal scored for the outcome of a match. In this case it is used to analyze the scorers from all over the planet.
This coefficient arises from the comparison of thousands of goals with the same score and the variation of the ‘chance of success’ obtained for the team that represents that goal. The base is covered by more than 40 leagues around the world, the first divisions of most of the countries of Europe and America and some second-order divisions, totaling more than 350,000 goals, hundreds of thousands of games in all kinds of competition of the last two decades.
Since football was created, the world has compared scorers based on various characteristics, but the most popular of all is based on the number of goals scored, and for some time now, it has also been analyzed based on the games you have played. A player who scores 10 goals in 15 games is not the same as another player who scores them in 25, but are we sure who is more decisive? He does not undertake to delve into the assists, or in different facets of the game that a scorer performs on the field to provide quality and significance to his team, it does not mean that they are belittling themselves at all. This analysis is dedicated to goals.
Analyzing data on the Internet, players with first-hand knowledge have been compared, because one follows them every week, and I was surprised that my views on soccer differed from the data provided by the statistics. Namely: both players shared similar statistics, the same number of goals for shots, for shots on goal, shots per game, goals for 90 minutes, and even in some cases, the player who seemed worse to me was slightly superior in some. Of course the data are not conclusive, they serve in their measure and context to be able to appreciate in a broader way some facets of a player and also to cover “scoutings” with more players than one can analyze with just two eyes videos.
These statistics are great for analyzing “how much”, but not “how”. In order to continue analyzing the player, one must enter the games and observe the kind of goals he did, and here comes the creation of xD. Because scoring 6–1 is not the same as scoring a 2–2 away. But how is that measured? How do we determine, how do we value each goal in each situation? In the first scatter box (Fig1) we can see that Cristiano and Lionel have the same number of goals, but despite that, Lionel’s goals average a higher xD, they are more decisive.
The xD contemplates both Home and Away goals in a different way, because the statistics mark that discounting from home 1–2 gives a different probability of winning for the home than if the visiting team takes a 2–1 advantage. The probability of the first result that the local wins is 9.8%, but if the visitor scores for 1–2, the local has a 7.16% probability of winning. The mental factor is evident in the results, and in the locality as well.
Scoring 6–0 does it help? Absolutely nothing, but scoring 5–4 to win the game is possibly the most decisive goal in a soccer game. The xD looks at each of the results and helps to easily determine which goals are worth more and which are not so much.
Applications
The interesting thing about this coefficient is that we can analyze the seasons of each player and observe how decisive it was for his team in it, we can analyze which players are the most decisive (always when scoring goals, I do not want to stop highlighting it) In each competition, we can analyze the level of determination that a player has regarding his team, or his league, even his country.
