Characterisation of offensive and defensive game play trends in the Australian Football League (1999-2019)

The aim of this study was to characterise and quantify offensive and defensive game play in the Australian Football League and analyse how it has evolved from 1999-2019. Nine offensive and twelve defensive variables were selected to represent their respective styles of play. Season averages for each variable were collected as well as an overall 21-season average and standard deviation. Offensive and defensive z-scores were calculated for each season and plotted relative to time. Offensive and defensive z-scores for each season showed a trend of an increase and decrease in offensive and defensive game play, respectively, up until about 2005-2007. These play pattern trends then clearly reversed and continue to evolve towards less offensive and more defensive game styles. Despite rule and interpretation changes to temper these trends, the 2019 season was the most defensive and least offensive in the period of review. Overall offensive game play has decreased across the period 1999-2019 while defensive game play has increased. Offensive play, however, was shown to be more closely related to success when compared to defensive play. This study provides a quantitative method of characterising offensive and defensive game play in Australian Rules Football.