  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.
