When assessing players, I usually use Understat as a free source for expected goals (xG).
So what exactly is Expected Goals?
Fundamentally , it’s a way of assigning a value based on a range of data. The higher the xG , the more likelihood of the opportunity being taken. So if a chance is 0.6xG, it should be scored 60% of the time. Get it !
Let’s be in honest, in low scoring game, the final score does not always provide a clear picture of the team or a player performance. Hence why more FPL managers and content creators turn to advance models like xG.
With Understats, in their own words their ‘goal is to create the most precise method for shot quality evaluation’. To achieve this they’ve ‘trained neural networks prediction algorithms with the large dataset (>100,000 shots, over 10 parameters for each)’. Not only do they have xG data for premier league but also for the top European leagues such as La liga, Bundesliga, Seria A, and so on.
So if you looking for free source for expected goals, than Understat is the platform for you. However, please bear in mind Understat does not derived their data using Opta stats.