Did too much tackling hurt St Kilda’s chances of winning last season’s flag? It is possible, if chasing tail came at the expense of creativity? For example, in the first 11 home and away rounds, the Saints set AFL benchmarks for combined defence and attack, with an average of 68 tackles a game and 106 points scored.
However, in their next 11 games, the pendulum tipped notably in favour of defence with an even higher tackle count of 76 a match while their scoring dropped to 94 points per outing. This swing continued during their three finals, when they registered 81 tackles a game and averaged only 69 points. St Kilda’s 2009 achievements, based on its supreme defensive effort, prompted a growing chorus hailing tackle counts as a critical measure for winning games.
However, the evidence says otherwise. Using the tackle-count ‘winner’ as a guide to who will win games is tricky. First, the published numbers are only raw statistics. There is no separate classification as to relative effectiveness. And second, even a simple calculation such as the table of average team tackles for 2009 highlights why raw tackle numbers don’t count as much as often assumed. Yes, St Kilda’s season average of 72 is significantly higher than the rest (see table), but premier Geelong ranked only sixth. The Western Bulldogs, Collingwood and Adelaide all made the final eight and ranked just below the competition average for tackles.
A plausible correlation between team tackling averages and premiership ladder success does not exist. Never has. The reason is simple. It’s generally better to have the ball than not have the ball and tackling is often an indicator of being second-to-the ball, chasing tail and an overly defensive mindset.
Various studies by respected sport mathematicians have confirmed this principle. Taking into account all games played in a season, these studies confirm that winning the tackle count results in just a whisker above a 50-50 chance of winning a game. A more recent study by sport mathematicians goes further in challenging tackling assumptions. The record-breaking average of 124 a game in 2009 compared to the combined previous three-season average of 103 a game does not mean tackles have suddenly become more important for winning games.
His correlations between tackle differences and score margin for each of the past 10 seasons shows no significant change occurring. A more plausible explanation for this leap in tackling in 2009 is the concurrent increase in the number of handballs, ineffective kicks, interchange and rugby-style scrimmages of play creating more chances for tackling. Greater insight is possible if there were a distinction between the quality and significance of tackles. But this is not officially available and the current definition is rather vague: When a player stops an opposition player with possession of the ball from getting his kick or handball away in a legal manner, or reduces the effectiveness of the opposition’s disposal.
Often the subjectivity of calling tackles within an acceptable range of accuracy is a challenge, notwithstanding the sophistication of today’s software capture systems. Now, with the aid of technology, identifying the relative effectiveness of tackles can be done. The highest rating should be awarded to any tackle resulting in a direct turnover of possession (frees for included), stoppage, goal-saver or match-saver. The next grading are tackles that effectively ruin a kick or handball, when the player in possession has prior opportunity.
A critical distinction here is the tackle occurs when the play is active. Far more problematic is classifying the large volume of tackles occurring in the frequent rugby-style scrimmages of play when a player takes possession with little or no prospects and is immediately wrapped up. No one doubts the Saints’ brilliance in all three categories of tackling and I am sure they will continue on this path in 2010. But they must also rediscover their creative genes. They have two remarkable stars showing the way creatively and defensively – Lenny Hayes and Nick Riewoldt.
Ted Hopkins is a Carlton premiership player and founder of Champion Data. His current project is TedSport, a high performance data analysis and consulting service.
This column was first published in the AFL Record. Copyright AFL 2010.