Coach-rated importance of technical performance metrics across playing positions in football: introducing the Game Performance Index (GPI)

Abstract

Introduction: Football is a dynamic and complex sport in which player impact is not always adequately captured by traditional performance statistics. While existing research has demonstrated the value of combining expert judgement with statistical methods, limited attention has been given to how coaches themselves prioritise technical skills across different playing positions. This study addresses this gap by examining coach-rated importance of technical actions by position and introducing the Game Performance Index (GPI) as a conceptual position-specific framework for structuring these evaluations. Methods: Seven experienced coaches and analysts from Rangers Football Club participated during the 2023/24 season. Participants rated the importance of positive and negative technical skills (e.g., successful dribbles, unsuccessful progressive passes, aerial duels won) across six outfield positions (centre back, full back, defensive midfielder, attacking midfielder, winger, and centre forward) using a five-point Likert scale. The analysis focused on the Professional Development Phase (PDP), incorporating match data from 23 players across 30 fixtures. Descriptive statistics were used to assess agreement patterns, while regression modelling and analysis of variance examined differences in importance ratings by skill type and participant. Participant deviation analysis was used to explore individual differences in rating behaviour. Results: Clear positional patterns emerged in how technical actions were valued, alongside notable overlap across roles. Defensive actions such as aerial and defensive duels were prioritised for centre backs and defensive midfielders but were also rated as relevant for forwards and wingers involved in pressing and defensive transitions. Attacking actions including chance creation, dribbling, and progressive passing were highly valued for attacking roles and remained important for deeper positions such as full backs and defensive midfielders, reflecting their role in build-up play. Differences in importance ratings were driven primarily by individual coaching tendencies rather than systematic differences between skill types. These findings illustrate that coach evaluations are shaped by positional demands and individual emphasis rather than a single uniform weighting structure.