Context Is Key: How Constraints Can Tell Us More About Kicking Effectiveness In Australian Football
The context on why something occurred is much more valuable than just knowing what occurred
By Peter Browne
Can context tell us more?
What ‘things’ contribute to effective actions in sport? A simple question, with a less than simple answer! Historically, athletic performance has been measured by ways of cumulation - like, how many offloads a rugby union player performs during a game or how many successful 3-pointers a player performs during a basketball game. Now, while this information is important, it can only take us so far when it comes to helping coaches design training activities. More directly, coaches need more than just accumulated actions of kicks or passes - they need to know the context of them to make sure those contexts can be recreated in training sessions!
Australian football is no different to those sports listed above, with kicks traditionally being recorded as effective (i.e., hits the intended target) or ineffective (i.e., misses the intended target). But as expected, there is way more to the story than just effectiveness… We know this by simply watching highlights from a match - some kicks are simple and unopposed passes, some are riskier to move the ball into a scoring position, and others are intended to move the ball quickly to put the defence out of position. Going further, we can ask ourselves questions like: was the player being tackled? Were they kicking to a contest? How much time did they have to kick the ball?
Therefore, knowing the context, driven through questions like those above, can give meaning to match statistics like kicking efficiency, taking their interpretation and utility to deeper and more practical levels. Yep, knowing the outcome is important (especially for commentators!), but understanding the context of the kick is critical if we are to design practice tasks intended to improve a player’s kicking skill.
Constraints can provide context
The context on why something occurred is much more valuable for designing practice tasks than just knowing what occurred. To know why a player attempted a particular kick, we need to know things like how much space was available near the intended target, how much pressure the kicker was under, the score in the game or where on the field the kick happened. All of the things listed above are examples of the constraints that the kicker operated within, and these shape how skills emerge in matches. Broadly speaking, constraints are things that shape skilled actions, either positively or negatively. Therefore, the measurement of constraints can give us the level of detail we need to gain a more complete picture of what goes into an effective and ineffective kick.
Recently, we look at this in some detail in a paper published in Human Movement Science. In this paper, we looked at the influence of six different constraints (listed in Figure 1) on 30,000 field kicks. Of these kicks, just over half were effective. We then compared the constraints and their effect on kick effectiveness across three developmental levels: elite under 18, state league and in the AFL.
Figure 1. A breakdown of constraint categories. Each kick is assigned one value from each category. Reprinted from Robertson et al. (2019). Copyright 2019 by Taylor & Francis Ltd.
What led to a kick being effective or ineffective?
As expected, each of these constraints were found to influence kick outcome, but when we looked a little further, we noted that it was their interaction that was critical for determining a kicks (in)effectiveness. For example, while being under physical pressure reduced a player’s capability to kick effectively, the pressure was mitigated if they had more time leading up to the kick to look for their passing options. Thus, as shown in Figure 2, understanding these constraints and their interaction enables a more complete picture of each kick and its efficacy.
Figure 2. Example of how accounting for additional constraint variables alters the mean efficiency of the kick outcome. Percentage values indicate confidence level of an effective kick under those constraints. Reprinted from Browne et al. (2019). Copyright 2019 by Elsevier Ltd.
What does this tell an AFL club?
Well, firstly, a player kicking at 40% effectiveness is traditionally considered to be below average. But, when we consider all the constraints that could be shaping their kicking, 40% may very well be pretty impressive! Simply, understanding the constraints that shape kicking effectiveness could offer AFL coaches with detailed information beyond just a number related to effectiveness.
Secondly, given that we found the influence of constraint interaction on kicking effectiveness differed between developmental levels (i.e., AFL and junior competitions), kicking efficiency under constraints could be used to create benchmarks for performance at different competition levels. For instance, if a junior player is outperforming league-wide benchmarks, coaches and recruiters might get interested in promoting or recruiting them. Further, this allows recruiters and list managers to more easily compare players between opposition teams.
Thirdly, by knowing which constraints (and their interaction) impact kicking effectiveness, a coach can design tasks that are more similar to what players may experience in a match, meaning training can be more game-like. For example, if a player is struggling with quick kicks whilst under opponent chasing pressure, coaches could incorporate more of those situations into training tasks. This could also lead to the design of more individualised training plans, while enabling detailed developmental monitoring and player progress.
So, to wrap up, constraints are critical for us in understanding the context of actions in a range of sports. Measuring them could open the door for a detailed appreciation of the how and why of certain actions, which could lead to greater support for coaches and talent recruiters when facing the tasks of designing practice activities or picking the next super star of the competition!