To assess the competitiveness of the English Premier League over time, I calculated the standard deviation of the final points table in the period from the 1995/6 season up to and including the 2022/3 season that has just concluded. This time period allows for direct comparison as there were 20 teams in the Premier League in all seasons.
Let’s begin by imagining two theoretically possible but highly implausible scenarios. Imagine if the Premier League contained teams of such similar quality that all games ended in a 1-1 draw. This extremely competitive league, with all games extremely finely balanced, would yield a final table in which all teams acquired 38 points. The “standard deviation” is a statistical measure of how much variation there is around the average. In this example, given that all teams are on 38 points the average points would be 38. And given that no team got anything other than 38 points, there would be no deviation from the average of 38, resulting in a standard deviation of zero.
Imagine another scenario in which one team was so bad that it lost all its games (achieving zero points) and another team was so good that it won all its games (114 points). And the remaining teams were positioned at equal six point intervals between these two positions (one team on 6 points, one of 12, one on 18 and so on). The result would be a final table with a large degree of variation between the points achieved by the teams (standard deviation of 35.5). This highly uncompetitive and imbalanced league has a large stretch of difference between the good teams and the bad teams.
Unsurprisingly, the actual real world standard deviations in the 1996-2023 period sit between these two extremes, and range from a low of 12.04 to a high of 21.01, as illustrated in the graph. Interestingly, the graph shows a strong linear relationship between time and the standard deviation for each season, with the standard deviation clearly increasing over time. There is a strong statistical relationship: time explains 44 percent of the variation in the standard deviations (and the relationship is statistically significant (p=.000)).
For example, in the opening period, up to and including 2004, all of these nine seasons had a standard deviation of less than 17, and four of them were less than 15. In the final nine seasons of this time period, four were over 19, two were between 17 and 19, and only three were less than 17 (with none less than 15).
What this increase over time in the standard deviation shows is that the Premier League is becoming more imbalanced, with increasingly large differences between the good teams and the poor teams. This increase in imbalance indicates a clear decline in competitiveness in the Premier League.
The Premier League in this 1995/6 to 2022/3 period has always been dominated by a very small number of teams. In the earlier years it was Manchester United (competing with either Arsenal or Chelsea) and in the later years it is Manchester City (with competition from either Chelsea or Liverpool). But, crucially, what the above graph shows is that in addition to being dominated by a small number of clubs the Premier League has now become more imbalanced, or less competitive, over time – with a bigger stretch in the final table between the relatively good teams and the relatively poor teams.
What one makes of this depends upon one’s taste. Perhaps it is not a problem, if one likes the idea of the best teams not only being good but also becoming, via a judicious blend of money and managerial ingenuity, so good that they are almost unbeatable. Alternatively, it is a problem if you like the idea that all games should be fairly finely poised, with the result pretty hard to call in advance.
Either which way, the trend is clear: imbalance is increasing and competitiveness is decreasing.
Image by Kelvin Stuttard from Pixabay.
