1. Introduction
Soccer is one of the most popular sports in the world. In elite soccer, to achieve success in league rankings, a team must win the highest number of matches, influenced by game indicators/game actions (e.g., free kicks, cards, ball possession, shots, corner kicks, goalkeeper saves, fouls committed, or offsides) [
1]. For this reason, there are assistants who collect statistical data from both their own, and the opposing, players, to identify potential strengths and weaknesses [
2]. The authors of this paper highlight the influence of the aforementioned game indicators on the final result of a match, and how they thus become performance indicators. In addition, the opponent’s quality and the match location are situational variables that can influence the performance of players and soccer teams [
3].
Some of these game indicators and situational variables have been studied in the Spanish league, LaLiga [
2]. The study [
2] shows that the match location influences the final result in favor of the home team. A similar study [
1] indicates that the match location, the effect of scoring first, and the quality of the opposing team influence the final result. Home teams are motivated by their fans, creating a feeling of territoriality, and visiting teams are pressured [
4] during matches. This means that home teams tend to take more shots and, therefore, the opposing team’s goalkeeper makes more saves [
5]. The differences in the movement profiles (intensities) in matches depending on the quality of the opponent have also been studied in the elite Spanish soccer leagues, in the First and Second Division [
6], and the Second B Division [
3]. Furthermore, it has been shown that teams participating in international competitions (e.g., the Champions League or the Europa League) are composed of coaches, assistants, and players who are more likely to withstand pressures, such as playing in crowded stadia, playing outside of the country, long-distance travel, etc. [
7,
8].
The COVID-19 pandemic interrupted the major European soccer leagues in mid-March 2020. The first league to resume competition was the Bundesliga on May 16. Subsequently, other European leagues resumed competition (e.g., LaLiga, the Premier League, Serie A, etc.). Except for the Russian League (at 10% capacity in each stadium), these leagues resumed competition without the attendance of fans [
9]. Specifically in LaLiga, the competition was interrupted in March (the 27th round), and resumed on June 8 [
7]. The COVID-19 pandemic brought major changes to the elite soccer leagues after their resumption. As a result, the Fédération Internationale de Football Association introduced new rules: (1) the banning of fans, in so-called ghost matches, or matches with a very limited fan attendance [
9], and (2) an increase in player substitutions from 3 to 5 players [
10]. For these reasons, the COVID-19 pandemic presents a unique situation in history for investigating the influence of game indicators that occurred in elite soccer matches.
Regarding performance in elite soccer matches, the current results on the effects of the COVID-19 pandemic report that the home advantage decreased in ghost matches [
11,
12]. In this regard, the number of fouls committed, and cards shown to visiting teams decreased, as the result of a lesser perceived social pressure on referees from the stands [
13]. Moreover, a study on the four major leagues (i.e., Bundesliga, LaLiga, the Premier League, and Serie A), comparing statistics from before and after the COVID-19 pandemic, indicates a decrease in the expected points and goals scored by the home team. The decrease in the home team’s advantage is due to the absence of fans in the stadium during the COVID-19 pandemic [
14]. In other words, the performance of the home team is halved when the stadium is empty [
7]. Nowadays, with stadia again crowded with fans, the video assistant referee helps referees in their decision-making during matches [
15]. It can only be used in the following four basic situations: (1) goal, (2) penalty, (3) red card, and (4) player mix-up (in awarding a yellow, yellow–red, or red card) [
9].
The results of soccer matches can be influenced by different game indicators [
1,
3,
16]. This study analyzed, independently for the pre-COVID-19, COVID-19, and post-COVID-19 periods, the influence of game indicators on the partial (Study 1-S1) and final (Study 2-S2) ranking of Spanish LaLiga teams over seven seasons. The statistical differences between the pandemic periods were also identified in the two studies. For each pandemic period, we hypothesized that: (1) in the partial ranking, there would be differences in the game indicators between balanced, unbalanced, and very unbalanced teams (S1); (2) in the final ranking, there would be differences in the game indicators between the Europe, mid-table, and relegation teams (S2); and (3) in both studies, there will be differences in these game indicators between the pre-COVID-19, COVID-19, and post-COVID-19 periods, according to the team’s ranking.
4. Discussion
Soccer is dominated by game indicators that can influence the performance of teams [
1,
3,
24]. Therefore, this study analyzed, independently for the pre-COVID-19, COVID-19, and post-COVID-19 pandemic periods, the influence of game indicators on the partial (S1) and final (S2) ranking of LaLiga teams over seven consecutive seasons. Additionally, the statistical differences between pandemic periods were identified. The main results reported that, according to the partial ranking, there was no or a small effect on these game indicators that was statistically significant for each pandemic period. So, hypothesis 1 was rejected. According to the final ranking, an intermediate effect and a large effect were obtained in some game indicators that were statistically significant (pre-COVID-19 period: the ball possession, shots on goal, and total passes; COVID-19 period: the ball possession, dangerous attacks, and total passes; post-COVID-19 period: the total shots, shots on goal, attacks, dangerous attacks, ball possession, and total passes). For this reason, hypothesis 2 was partially accepted. In addition, the pandemic period*ranking interaction only reported intermediate and large effects in terms of the final ranking. Therefore, hypothesis 3 was partially accepted. The mentioned indicators were decisive to reaching a Europe position at the end of each season and pandemic period, especially the ball possession and total passes. They had a greater influence on the final ranking than on the partial ranking.
In the pre-COVID-19 period, our results reported that the most prominent game indicators, in favor of the Europe teams, were the ball possession, shots on goal and number of total passes, with an intermediate effect. In the same competition, Fernández-Cortés et al. [
2] indicated that teams who won at home played with more ball possession, and made more shots on goal, among other factors. Ball possession has previously been identified as marking out the top-ranked teams in both the Chinese Soccer Super League [
25] and the UEFA Champions League [
26]. It is possible that teams ranked in Europe spend more time ahead on the scoreboard than their opponents [
26]. This could mean that, when they are winning, they are not in a hurry to score a goal or reach the opponent’s area, assuming a strategy of keeping the ball and slowing down the game [
27]. Moreover, this strategy involves making a greater number of passes [
25]. The indicators of ball possession and total passes are positively associated with the shots on goal [
28]. Ball possession leads to better collective play and optimal shooting positions, and also limit the opportunities of the opposing team [
29].
During the COVID-19 pandemic period, the most prominent game indicators, also in favor of the Europe-ranked teams, were possession of the ball and dangerous attacks, with an intermediate effect; and the number of total passes, with a large effect. As can be seen, the first two pandemic periods followed a similar trend. This could be because the teams did not have time to adapt to the new changes in the way of playing. In general, Europe-ranked teams would have a higher technical level/quality [
30]. This led to a higher ball possession, linked to the total number of key passes [
25]. In the major European competitions (i.e., Ligue 1, Serie A, LaLiga, the Premier League, and Bundesliga) during the 2019/2020 season, with fans in the stadia (before the restrictions), home teams scored more goals than visitors [
7], because the number of dangerous attacks was higher. In contrast, another study [
14] comparing the pre-COVID-19 and COVID-19 period in European soccer matches showed a decrease in the goals scored by home teams in ghost matches, which also affected the points and ranking. Another indicator that was affected during the COVID-19 period, in similar studies [
9,
12,
13], was the higher number of fouls committed by home teams which, in turn, resulted in more yellow cards. It was essential to work on set pieces because, given the increase in this game indicator during the COVID-19 period, they became of great importance to the result [
31]. The absence of fans and noise caused coaches and players to adapt their behavior to the empty environment in which they operated [
32].
In the post-COVID-19 period, the most prominent game indicators, again in favor of Europe-ranked teams, were the total shots, shots on goal, attacks, and dangerous attacks, with an intermediate effect; and the total passes and ball possession, with a large effect. In the three pandemic periods studied, two interrelated game indicators stood out: the ball possession and total passes. Both game indicators, together with the attacks, were higher in the post-COVID-19 period, compared to the other two pandemic periods. The dangerous attacks were higher pre-COVID-19, compared to during COVID-19 and post-COVID-19. This last pandemic period differed from the rest, because there was an even greater interest on the part of the teams in maintaining possession of the ball and avoiding direct play, associated with more attacks and, therefore, greater possibilities of shots [
28]; or in retaining the ball when they were winning [
27]. In this particular period, the higher-ranked teams controlled the ball more, and imposed their style of play [
6,
33,
34]. In this regard, in the major European leagues (i.e., Ligue 1, Serie A, LaLiga, the Premier League, and Bundesliga), the ball possession, number of key passes, and scoring first were correlated with the accumulation of goals scored and the points at the end of the season [
16]. In turn, Yang et al. [
33] reported that lower-ranked teams performed more defensive actions, especially in unbalanced matches.
The main differences found in this study were in the attack indicators, and not in the defense ones. This could be because teams tend to opt for the strategy of keeping possession of the ball, to achieve victories. It has been shown that higher-ranked teams show higher ball possession [
25,
26], and lower ranked teams show lower ball possession [
33]. Maintaining ball possession implies an increase in attacking actions [
28]. Despite this, it requires precision on the part of the teams, and the teams with the best technical/quality level achieve this [
30]. In addition, when in possession of the ball, the teams defend simultaneously. As a result of this study, soccer coaches are advised to choose a technically sound starting eleven that allows them to maintain ball possession, i.e., to have few losses per match. In this way, they will be able to stay in the top positions for a season. For managers, it is important, when recruiting players, to know that these game indicators are fundamental for a team to be in the upper part of the ranking. In addition, the more players with these profiles a team has, the easier it will be to obtain a better final ranking.
Limitations, Practical Applications, and Future Studies
Among the limitations, it should be noted that, among the major European leagues, this study collected data only from LaLiga. Despite the existing equality at the scorer level among the major European leagues [
34], it is not possible to generalize our results to other leagues.
The notational analysis allowed the identification of the game indicators that should be reinforced to increase the probability of success (a better ranking). Following this line of thought, according to our results, LaLiga teams should play with more ball possession, related to the total passes. A greater possession of the ball allows them to take more shots (offensive actions), and thus to have a better chance of winning. This information is of interest to coaches and soccer assistants when preparing and directing matches.
Controlling the competitive balance in soccer is difficult, due to its rapid evolution. In this vein, team dynamics change between seasons, or even within a season [
9]. Further research is needed to confirm the results obtained in this study. Moreover, it would also be interesting to analyze intensities according to the quality of the opponent.