GSAX
also: goals saved above expected · GSAx · GSAA
Expected goals against minus goals actually allowed — how many goals a goalie saved that an average goalie would not have.
GSAX = expected goals against − goals againstSave percentage treats every shot the same, so a goalie behind a team that gives up slot chances looks worse than one facing point shots, whatever either of them does. GSAX fixes that by scoring each shot for quality first: face harder shots and more is expected of you.
Positive is above average. Around +20 over a season is an excellent year and the best reach the high twenties or thirties. It is calibrated within each season, so league GSAX sums to zero every year and a goalie is measured against his own peers rather than a different era.
As a check on whether it is measuring anything: the season leader here is a Vezina winner or the consensus analytics pick in every season tested — Price in 2014-15, Gibson in 2017-18, Hellebuyck in 2019-20 and 2023-24, Shesterkin in 2021-22.
Reading small gaps as real. The model slightly over-rates the most dangerous chances, so a goalie facing an unusually high-danger workload is flattered. A two-goal difference between two goalies over a season is noise.
Where to get it
Related
GSAX from the API
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