Assessing competitive balance in the English Premier League for over forty seasons using a stochastic block model

Abstract

Competitive balance is of much interest in the sports analytics literature and beyond. We develop a statistical network model based on an extension of the stochastic block model to assess the balance between teams in a league. We represent the outcome of all matches in a football season as a dense network with nodes identified by teams and categorical edges representing the outcome of each game as a win, draw, or a loss. The main focus and motivation for this paper is to assess the issue of competitive balance in the context of the English First Division / Premier League over more than 40 seasons. Our analysis provides evidence suggesting a structural change around the early 2000s from a reasonably balanced league to a two-tier league.