In football, however, the rules of play allow for teams to score easily and, unlike basketball or netball, teams do not take “turns” with the ball to have opportunities to score. This means that propensities of teams to score or concede points can deviate much more than when the rules give each alternate “turns” – in football, each team requires skill to gain a “turn” at scoring. In fact, as Loek Groot shows in ‘Some Determinants of the Natural Level of Competitive Balance in European Football (Soccer) and US Team Sports: The Role of the Referee, the Scoring Context and Overtime’, a team with half the propensity to score of an competition’s average team would expect a winning equivalent no higher than 2 percent (a practically certain winless season in real-world football schedules) as against 20 percent in rugby and 35 percent in soccer. To put it another way, for the same disparity in win percent team qualities would need to deviate twice as much in rugby as in football.
The problem of not considering an upper limit for standard deviation was noted by P. Dorian Owen in ‘Limitations of the relative standard deviation of win percentages for measuring competitive balance in sports leagues’. Football, crucially, differs from baseball, ice hockey or soccer in that plausible differences in team qualities could easily produce probabilities of winning equal to or negligibly different from 0 or 1, as observed when Hawthorn during its early years as a League club faced the “big three” of Carlton, Collingwood and Richmond. However, at the same time one should not ignore the fact that if teams were equal in winning probability they would not all win the same number of games – especially in short-season sports like football.
Thus, as a new measure of competitive balance I propose the following steps:
- Calculate what Dorian Owen symbolises ‘ASDub’ or the standard deviation of a perfectly unbalanced league
- Owen demonstrates for us that ASDub = ((n+1)/(12*(n-1)))½ where n is number of teams
- The ISD as based on the simple binomial distribution is give by (4l)½/4l where l is number of games per season or average number for unequal schedules
|(ASDactual-ISD)/(ASDub-ISD) ratios for the three largest (Australian rules) football leagues between 1898 and 2013.|
Note: the zeroes for the SANFL are seasons without regular play during the World Wars (1916, 1917, 1918, 1942, 1943, 1944).
The fact that the pre-World War I period without equalisation by zoning or revenue sharing was – despite much lower scoring than later eras – quite close to the hypothetical perfectly unbalanced league implies:
- that without these regulations football would with higher scoring have acquired (ASDactual-ISD)/(ASDub-ISD) ratios consistently negligibly different from positive unity, and/or
- that reduced variation in team qualities after World War I led stronger teams to play more attacking football and thus increased scoring
- a proposition supported by more defensive tactics since Docklands supplanted Waverley. This change eliminated opportunities for shorter players of value in wet or windy conditions, made very tall people of limited supply more valuable, and almost certainly increased discrepancies in team qualities.
- = (31/(12*29))½
- = (31/348)½
- = ((31/348)½)/((328)½)/328)
- = ((31/348)½)*(328/(328)½))
- = ((31/348)½*(107584/328)½)
- = ((31/348)½*(328)½)
- = (10168/348)½
- = (2542/87)½
- ≈ 5.40540385
|These are the raw Noll-Scully ASD/ISD ratios for the “major” football leagues since 1898 (again, the zeroes in the SANFL data are wartime seasons without regular football)|