Introduction: Coaches are usually central to team performance and player selection, however, their observations and judgements may be also be useful to the medical team where functional screening for injury prevention and recovery typically occur. This study aimed to assess whether soccer coaches' assessment of their players' physical skills is associated with the players’ physical performance on formal performance testing during pre-season.
Methods: Soccer players were rated subjectively by two coaches independently. The coach's subjective rating applied their expert opinion to score different movements and skills of the soccer players (technical, tactical, physical and psychological). Each player was rated out of 100, as compared to the coach's perceptions of the world's leading players in those positions. The ratings were the mean of two coaches' observations to produce one rating for each participant. The Intra-class Correlation Coefficient (ICC) was utilised to assess the reliability of the inter-coach ratings. Player scores on four common functional tests were evaluated by team medical staff independently of the coaches' ratings. The four functional tests assessed were the Y-balance test (normalised anterior, posteromedial, and posterolateral), triple medial hop, triple forward hop, and hexagon agility test. Decision tree analysis was deployed to determine: 1) How closely coaches' ratings of physical aptitude are associated with functional testing scores. 2) What cut-off values best discriminate between higher and lower coach ratings.
Results: Sixty-three male professional soccer players (23.08 ± 1.34 years) from the Saudi Professional League volunteered to participate. The ICC values ranged from 0.73 to 0.79. for the coach ratings of physical skill, indicating good to excellent agreement between the coaches. The tree model demonstrated that functional performance scores and coach rating of physical skill agreed in 86% (54/63) of ratings, 88% precision and 91% recall. The confusion matrix shows that the algorithm using functional testing scores correctly rated 88.4% of players classified as high physical performers by their coaches, and 80% of lower-rated players. The decision trees provided cut-off scores where high physical performance ratings from the coaches were given to 42 out of 63 players. The cut-off scores that best discriminated between higher and lower coach ratings were; average bilateral anterior normalised Y-balance test greater than 63.7 cm, and average bilateral triple medial hop between 408.3 cm and 481.7cm; and average bilateral posterolateral normalised Y-balance test greater than 88.2 cm.
Conclusion: Qualitative judgement of physical skill by coaches closely matched independently measured functional performance tests in this study. Findings from this study could be used to assist in player selection and preparation criteria.
Impact and application to the field:
- •Both general and sport-specific player capabilities can be evaluated through physical testing.
- •Sporting teams should take advantage of the coach rating scales of soccer players to enhance player return to play post-injury.
Conflict of interest statement: My co-authors and I have no conflict of interest of relevance to submitting this abstract.