The Relative Importance of Ability, Luck and Motivation in Team Sports: a Bayesian Model of Performance in the English Rugby Premiership

TL;DR

This paper introduces a Bayesian hierarchical model to quantify the roles of ability, luck, and motivation in rugby match outcomes, highlighting effort as a key factor influencing scores in the English Premiership.

Contribution

It presents a novel Bayesian model that incorporates motivation, specifically effort, to better explain team performance beyond ability and luck.

Findings

Effort significantly influences match outcomes.

Motivation plays a crucial role alongside ability and luck.

The model improves understanding of performance determinants in rugby.

Abstract

Results in contact sports like Rugby are mainly interpreted in terms of the ability and/or luck of teams. But this neglects the important role of the {\em motivation} of players, reflected in the effort exerted in the game. Here we present a Bayesian hierarchical model to infer the main features that explain score differences in rugby matches of the English Premiership Rugby 2020/2021 season. The main result is that, indeed, {\em effort} (seen as a ratio between the number of tries and the scoring kick attempts) is highly relevant to explain outcomes in those matches.