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

TL;DR

This paper introduces a statistical network model based on an extended stochastic block model to evaluate competitive balance in the English Premier League over 40 seasons, revealing a shift from balance to a two-tier structure around the early 2000s.

Contribution

It develops a novel statistical framework using a stochastic block model extension to analyze league competitiveness over multiple seasons.

Findings

Evidence of a structural change in league balance around early 2000s

Identification of a shift from a balanced league to a two-tier system

Application of network modeling to sports league analysis

Abstract

Competitive balance is the subject of much interest in the sports analytics literature and beyond. In this paper, we develop a statistical network model based on an extension of the stochastic block model to assess the balance between teams in a league. Here 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 provide a statistical framework to assess the issue of competitive balance in the context of the English First Division / Premier League over more than 40 seasons. The Premier League is arguably one of the most popular leagues in the world, in terms of its global reach and the revenue which it generates. Therefore it is of wide interest to assess its competitiveness. Our analysis provides evidence suggesting a structural change around the early 2000's from a reasonably balanced league to a two-tier league.