Kicking for Goal or Touch? An Expected Points Framework for Penalty Decisions in Rugby Union

TL;DR

This paper introduces an Expected Points framework to optimize penalty decision-making in rugby union, considering field position and game context, supported by extensive match data and a model of penalty success.

Contribution

It presents the first comprehensive EP-based method for evaluating penalty strategies in rugby, integrating game context and player-specific factors.

Findings

Decision maps identify optimal penalty choices based on location and context.

The framework adapts to team-specific kicker and lineout performance.

Results suggest strategic shifts in penalty decisions depending on game situation.

Abstract

Following a penalty in rugby union, teams typically choose between attempting a shot at goal or kicking to touch to pursue a try. We develop an Expected Points (EP) framework that quantifies the value of each option as a function of both field location and game context. Using phase-level data from the 2018/19 Premiership Rugby season (35,199 phases across 132 matches) and an angle-distance model of penalty kick success estimated from international records, we construct two surfaces: (i) the expected points of a possession beginning with a lineout, and (ii) the expected points of a kick at goal, taking into account the in-game consequences of made and missed kicks. We then compare these surfaces to produce decision maps that indicate where kicking for goal or kicking to touch maximizes expected return, and we analyze how the boundary shifts with game context and the expected meters gained to touch. Our results provide a unified, data-driven method for evaluating penalty decisions and can be tailored to team-specific kickers and lineout units. This study offers, to our knowledge, the first comprehensive EP-based assessment of penalty strategy in rugby union and outlines extensions to win-probability analysis and richer tracking data.