An examination of expected goals and shot efficiency in soccer

Abstract

The aim of this study was to examine goal scoring in European football leagues and specifically which factors are associated with predicting Expected Goals (xG). This concept helps us to evaluate player, specifically strikers, in the number of goals they score season upon season. Therefore, this study examined the shots from the Premier League and Bundesliga games (380 & 306) from the 2012-2013 season. All of the shots were grouped into sections on the field of play and a theoretical goal value was applied to each area. The factors analysed were: distance of the shot taken from goal and the angle of the shot in relation to the goal. In calculating xG, it is suggested that the distance and angle of the shots matter. A combination of the two factors calculated xG better than each variable alone. Furthermore, this examination of xG has been able to identify mid-table teams scoring and conceding goals relatively accurately. Top league teams and lower league teams over and under achieved respectively. Managers and Coaches may find this method useful in identifying players who consistently score close to their expected total or even out-perform it.