  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.
