Analysis of Player Motion in Sport Matches

The system for analysis of player motion during sport matches, developed at University of Ljubljana will be presented. The system allows for non-intrusive measurement of positions of all players in indoor sports through whole match using only inexpensive video equipment - cameras mounted on the ceiling of the sports hall. Tracking process (obtaining trajectories from videos) is automatic and only supervised by operator, to initialize player positions at the beginning and correct the mistakes during the tracking. The software provides means for user friendly calibration of video data - using court markings of each supported sport (e.g. european handball, basketball, squash, tennis...) as reference coordinates. Manual annotations can be added, to complement the quantitative data. Software keeps synchronization between annotations and trajectory data and provides means to use custom annotation dictionaries. Due to calibration, the results are provided in court coordinates (meters, centimeters) and can be exported (synchronized with annotations in same file) for further analysis with any application (e.g. excel, SPSS). Software itself supports several kinds of graphical data presentations. If time allows, the software itself will be demonstrated with examples from different sports

Effects of rule changes on physical demands and shot characteristics of elite-standard men’s squash and implications for training

The physical demands and rally characteristics of elite-standard men's squash have not been well documented since recent rule changes (scoring and tin height). This information is needed to design optimal training drills for physical conditioning, provided here based on an analysis of movement and shot information. Matches at the 2010 (n = 14) and 2011 (n = 27) Rowe British Grand Prix were analysed. Rallies were split into four ball-in-play duration categories using the 25th (short), 75th (medium), 95th percentiles (long) and maximum values. Cohen’s d and Chi squared tests of independence evaluated effects of rally and rule changes on patterns of play. The proportion of long, middle and short shots was related to the duration of the rally with more shots played in the middle and front of the court in short rallies (phi = 0.12). The frequencies of shots played from different areas of the court have not changed after the adoption of new rules but there is less time available to return shots that reflects the attacking nature of match play for elite-standard men players. Aspiring and current elite-standard players need to condition themselves to improve their ability to cope with these demands using the ghosting patterns presented that mimic demands of modern match play

Using a situation awareness approach to determine decision-making behaviour in squash

Situation awareness (SA) refers to the awareness of all relevant sources of information, an ability to synthesise this information using domain knowledge gained from past experiences and the ability to physically respond to a situation. Expert-novice differences have been widely reported in decision-making in complex situations although determining the small differences in expert behaviour are more elusive. This study considered how expert squash players use SA to decide on what shot to play. Matches at the 2010 (n = 14) and 2011 (n = 27) Rowe British Grand Prix were recorded and processed using Tracker software. Shot type, ball location, players' positions on court and movement parameters between the time an opponent played a shot prior to the player's shot to the time of the opponent's following shot were captured 25 times per second. Six SA clusters were named to relate to the outcome of a shot ranging from a defensive shot played under pressure to create time to an attempted winner played under no pressure with the opponent out of position. This new methodology found fine-grained SA differences in expert behaviour, even for the same shot type played from the same court area, beyond the usual expert-novice differences

Profiling elite male squash performance using a situation awareness approach enabled by automated tracking technology

The pioneering research into squash performance by Sanderson and Way (1977) tested the hypothesis that “an individual exhibits a pattern of play which is relatively stable over time and independent of the opponent”. This belief influenced research in this area for many years. Many studies attempted to discover these stable patterns of play e.g. Hughes, 1985; McGarry and Franks, 1996; Hughes, Evans and Wells, 2001; and presented, what were suggested as indicative, playing profiles e.g. Murray and Hughes, 2001; Hughes, Watts, White and Hughes, 2006. This PhD aimed to analyse squash match play at a more detailed level by using movement data to supplement shot information related to shot types, court area etc. Elite male squash matches were filmed using a fixed overhead camera and images processed in software to semi-automatically calculate player movement information as well as allow an operator to manually input shot information. The two data streams were synchronised in Matlab before reliability and accuracy testing. Good levels of reliability were found for all court locations and shot information (agreement > 90%) although when an operator coded a long match without a break some percentage agreements had less than 90% agreement, presumably due to fatigue effects. Error testing, using a series of queries, specific to each data type, following data collection and prior to data analysis, discovered multiple errors in the data which were corrected. The physical demands and rally characteristics of elite-standard men's squash had not been well documented since recent rule changes (scoring and tin height). Rallies were split into four ball-in-play duration categories using the 25th (short), 75th (medium), 95th percentiles (long) and maximum values. The frequencies of shots played from different areas of the court had not changed after the adoption of new rules but there was less time available to return shots. Chapter 5 considered how expert squash players use Situation Awareness (SA) to decide on what shot to play. Shot type, ball location, players’ positions on court and movement parameters were captured 25 times per second for shots that achieved their objective. Six SA clusters were named to relate to the outcome of a shot ranging from a defensive shot played under pressure to create time to an attempted winner played under no pressure with the opponent out of position. The pressure exerted on a squash player is a coupling of the two players’ SA abilities. The same variables used for Chapter 5 were used except all shots (excluding serves and rally ending shots) were used, producing five main SA clusters, where a greater proportion of shots were categorised in the greater pressure clusters and less in the lower pressure ones. Individual matches were presented using cluster profile infographics which demonstrated how individual players played differently in different matches

The attacking process in football: a taxonomy for classifying how teams create goal scoring opportunities

The majority of existing Performance Analysis (PA) research has adopted a reductionist approach which considers only selected events such as the number of shots, passes or pass success rates in isolation for analysis (Mackenzie & Cushion, 2013). James (2009) also suggested the obvious problem associated with previous types of research is that simply analysing outcome measures cannot provide meaningful information for improvement without an understanding of the processes undertaken to achieve these outcomes. Understanding the patterns of play exhibited within a game can help coaching be more specific and objective to facilitate the improvement for tactical performances of teams (Tenga et al., 2015). Previous football research has traditionally measured the number of passes (Reep and Benjamin, 1968; Bate, 1988; Hughes and Frank, 2005) or duration of team possessions (Jones et al., 2004; Bloomfield et al., 2005; Lago and Martin, 2007; Lago, 2009) to determine playing styles of team. Although these methods identified different team playing styles, based on overall match statistics, the authors have typically not distinguished the “how” different attacking procedures evolved e.g. how teams initiate or develop build-up play, progress attacks and create goal scoring opportunities. Therefore, this thesis aimed to identify the attacking process to provide practically useful and objective information for applied practice. Study 1 established operational definitions for unstable situations (potential goal scoring opportunities) in football to differentiate stable and unstable game states. Validity tests were conducted by four football coaches and two performance analysts from a professional football club in the English Premier League to create robust operational definitions. After the completion of this process, five specific situations were deemed as unstable situations, which arose due to pitch location, game situation or a specific action i.e. 1) Penalty Box Possession (PBP), 2) Count Attack (CA), 3) Ratio of Attacking to Defending players (RAD), 4) Successful Cross (SC) and 5) Successful Shot (SS). Study 2 produced a framework for the attacking process to describe how all unstable situations arose from the start of each possession. The attacking process was categorised into three independent situations, stable (no advantage), advantage, and unstable (potential goal scoring opportunity) situations. Possessions that did not results in advantage or unstable situations were not analysed. English Premier League football matches (n=38) played by Crystal Palace Football Club in the 2017/2018 season were analysed as an exemplar. Results showed that Crystal Palace FC created a median of 53.5 advantage situations and 23 unstable situations per match. They frequently utilised wide areas (advantage) to progress their attack, which resulted in 26.6% unstable situations i.e. penalty box possessions and successful crosses. However, this was the lowest success rate compared to the other advantage situations. This study provided a novel methodology for classifying the attacking process with a scientifically valid approach for use in the applied world. Study 3 analysed all possessions for Crystal Palace Football Club in the 2017/2018 season, irrespective of whether advantage or unstable situations arose. This enabled the analysis of the influence of situational variables i.e. match venue, opposition quality, match status, key player’s appearance on the attacking process. Appropriate categorisations for independent variables were presented with one problem associated with some previous papers i.e. only using the end of season ranking for team quality (Lago-Peñas & Lago-Ballesteros, 2011; Almeida et al., 2014; Liu et al., 2015; Aquino et al., 2016; Mendez-Dominguez et al., 2019) amended. Crystal Palace had, on average, 91.3 stable, 54 advantage and 26 unstable situations from 114.8 possessions per match which resulted in 12.5 shots. Poisson log-linear regression explained that Crystal Palace created more midfield line breaks; more zone 14, wide area and penalty box possessions and less counter attack chances for different levels of each independent variable e.g. when playing at home compared to away. This suggests that strategy changes depending on the situation would be advantageous. Overall, this thesis aimed to provide useful information for the applied world and close the purported gap between academic and applied areas. This methodology will help teams better analyse opponent’s patterns for creating advantage and unstable situations. Future research should consider using the duration of possessions and pitch area information to further develop the usefulness of the model