# Leveraging the Chain on Goals Model in Football: Applications for Attack and Defensive Play
## 4 Discussion  
The data from this study offer valuable experimental evidence that can effectively inform the performance of football players and teams. With regard to the variables presented in Table 1, the primary finding was the establishment of reference values for the variables that constitute the chain on goals model in football (Table 2), applicable to the attack and defensive phases of teams in both the Spanish women's and men's football leagues. Notably, there is similarity between the two leagues. However, in the overall dimension, the defensive performance (average number of goals conceded per match) and GSAA were statistically different when comparing both leagues (\(p\) = 0.03 and \(p\) < 0.001, respectively) (Table 2). These significant differences had a medium and large effect size, respectively. Regarding defensive performance, the authors concluded that more goals were conceded in the women's league, indicating a weaker defensive system in this league. Concerning GSAA, this metric analyzes the balance between GK performance and shooter performance. A positive GSAA outcome indicates that the GK's performance is better than the shooter's, whereas a negative outcome suggests the opposite. If the GSAA value is \"0\", it signifies a neutral balance between GK and shooter [22]. Our data revealed that the men's league was balanced, as there was an equilibrium between the performance of the shooter and the GK. In contrast, the women's league exhibited an imbalance, suggesting a poorer performance by the GK. Concerning the second objective, the authors sought to present four practical concepts based on the metrics of the chain on goals model, aimed at assisting coaches and technical staff in better understanding a team's tactical performance and that of its players (Table 3). Figures 1 and 2 illustrated the analysis and interrelationships of these four concepts across all professional teams in the Spanish league, both women's and men's, during 2023-2024 season. One of the primary responsibilities of analysts is to thoroughly examine the data to review performance metrics, enabling coaching staff to pinpoint areas for improvement, such as missed opportunities, defensive weaknesses, or necessary tactical adjustments [23]. Therefore, by analyzing these concepts, we can discern whether football errors stem from the team's strategy or from individual player quality. Specifically, the concepts of \"off-ball movement\" and \"team's positioning\" provide insights into the team's strategy, while \"player's offensive quality\" and \"player's defensive quality\" relate to the quality of the individual players. Notably, the concepts defining the defensive and attack phases showed a low correlation. The authors suggest that this discrepancy arises because \"off-ball movement\" and \"team positioning\" reflect the overall strategy of the team, whereas \"player's offensive quality\" and \"player's defensive quality\" are indicative of individual player quality. As a result, the two sets of concepts operate independently from each other. Curiously, the two metrics reflecting information about team strategy differed significantly between the two leagues (\(p\) < 0.001 in both cases), with a large effect size in both cases. Regarding off-movement, the data indicated that PV was more decisive in the women's league, while xG was more critical in the men's league. This finding aligns with a previous study [15], which found that the predictive value of PV in relation to match outcomes in the Spanish women's league showed a stronger correlation than in the men's league. Concerning team's positioning, the data revealed that, from a collective perspective, the men's league demonstrated better defensive positioning than the women's league. The authors hypothesize that, while the football pitch dimensions are the same for both leagues, the physical dimensions of men and women players differ. Consequently, the ability to cover the playing field during the defensive phase may be greater in the men's league.