Performance Metrics for Ice Hockey Accounting for Goal Importance

Abstract

The evaluation of player performance is an important topic in sports analytics and is used by coaches for team management, in scouting and in sports broadcasts. When evaluating the performance of ice hockey players, many metrics are used, including traditional metrics such as goals, assists, points and modern metrics such as Corsi. One weakness of such metrics is that they do not consider the context in which the value for the metric was assigned. Other advanced metrics have been introduced, but as they are not easily explainable to practitioners, they may not make it into the hockey discourse. In this paper we introduce new goal-based metrics that (i) are based on traditional and well-known metrics, and thus easily understandable, (ii) take context into account in the form of time, manpower differential and goal differential and (iii) add a new aspect by taking into account the importance of the goals regarding their contribution to team wins and ties. We describe the intuitions behind the metrics, give formal definitions, evaluate the metrics using the eye test and show correlations to the traditional metrics. We have used data from the NHL seasons 2007-2008 to 2013-2014 and show which players stand out with respect to the number of goals and the importance of goals.