Comparing subjective and objective evaluations of player performance in Australian Rules football

Abstract

Player evaluation plays a fundamental role in the decision-making processes of professional sporting organisations. In the Australian Football League, both subjective and objective evaluations of player match performance are commonplace. This study aimed to identify the extent to which performance indicators can explain subjective ratings of player performance. A secondary aim was to compare subjective and objective ratings of player performance. Inside Football Player Ratings (IFPR) and Australian Football League Player Ratings were collected as subjective and objective evaluations of player performance, respectively, for each player during all 1026 matches throughout the 2013–2017 Australian Football League seasons. Nine common player performance indicators, player role classification, player age and match outcomes were also collected. Standardised linear mixed model and recursive partitioning and regression tree models were undertaken across the whole dataset, as well as separately for each of the seven player roles. The mixed model analysis produced a model associating the performance indicators with IFPR at a root mean square error of 0.98. Random effects accounting for differences between seasons and players ranged by 0.09 and 1.73 IFPR each across the five seasons and 1052 players, respectively. The recursive partitioning and regression tree model explained IFPR exactly in 35.8% of instances, and to within 1.0 IFPR point in 81.0% of instances. When analysed separately by player role, exact explanation varied from 25.2% to 41.7%, and within 1.0 IFPR point from 70.3% to 88.6%. Overall, kicks and handballs were most associated with the IFPR. This study highlights that a select few features account for a majority of the variance when explaining subjective ratings of player performance, and that these vary by player role. Australian Football League organisations should utilise both subjective and objective assessments of performance to gain a better understanding of the differences associated with subjective performance assessment.

Can Elite Australian Football Player’s Game Performance Be Predicted?

“…The official AFL player rating (AFLPR) produced by Champion Data (Champion Data Pty Ltd., Melbourne, Australia) was used as the sole game performance rating measure. This metric has previously been used in elite Australian football research (Fahey-Gilmour, Dawson, Peeling, Heasman, & Rogalski, 2019;McIntosh, Kovalchik, & Robertson, 2019;Ryan et al, 2018) while also being established as valid and reliable (Robertson, Gupta, & McIntosh, 2016). The AFLPR is objectively calculated on the basis of changes in 'field equity' (Jackson, 2016;McIntosh et al, 2019).…”

“…This metric has previously been used in elite Australian football research (Fahey-Gilmour, Dawson, Peeling, Heasman, & Rogalski, 2019;McIntosh, Kovalchik, & Robertson, 2019;Ryan et al, 2018) while also being established as valid and reliable (Robertson, Gupta, & McIntosh, 2016). The AFLPR is objectively calculated on the basis of changes in 'field equity' (Jackson, 2016;McIntosh et al, 2019). Field equity accounts for the contribution of a player's involvement in the play with reference to a series of contextual factors (e.g.…”

“…location on the ground, pressure under/applied) and whether the player's action then results in an increase or decrease in the team's expected chance of scoring (Jackson, 2016). This measure provides greater context to game involvements, potentially providing a better indication of a player's influence on the game than alternative statistical indicators (McIntosh et al, 2019). For a full description and detailed method of AFLPR calculation please see Jackson (2016).…”

“…Therefore, using a global model for all players may not be sensitive enough to ascertain these differences and other statistical methods should be investigated. At the very least, future research using the approaches established here may look to separate players into playing position, as has been done previously (Lazarus et al, 2017;McIntosh et al, 2019), to give a better reflection of the nuances that exist within the component parts of a team structure.…”

Age at Nomination Among Soccer Players Nominated for Major International Individual Awards: A Better Proxy for the Age of Peak Individual Soccer Performance?

“… McHale et al (2012) , for example, in an attempt to formulate a soccer player performance rating system, envisaged a hypothetical English National team chosen from the highest ranked players in each position, based on their index scores, and compared the hypothetical team against the actual English team appearing in the first game of the 2010 World Cup. Similarly, McIntosh et al (2019) validated objective performance indicators by comparing them with subjective ratings of player performance in Australian Rules football.…”