GSAx - some background information

 

I do not claim to be an expert on this stat, just intrigued by it. Traditional measures of evaluating goalies have been proven to be ineffective. Obviously the W-L record is the best example of this for reasons we do not need to get into. Save percentage seemed better, and of course it is, but it also does not include within it so much of what goalies actually face, as all shots against are considered equal, no matter the situation or where they come from on the ice. Other stats weight the save pct of a goalie against the league average. This may account for trends in goalscoring across seasons and decades, but does not account for the performance of a goaltender against every shot in a game. 

GSAx measures the potential scoring outcome of each shot given several factors, arriving at a total number of expected goals the goalie might allow, and then compares this to the number of actual goals allowed. 

Read more here - 

Adjusting how we Evaluate and Analyze Goaltenders

This article by Jake Zrihen does a great job of illustrating how GSAx is applied to the performance of a goaltender and is worth a read.

Evolving Hockey

This site (click on "Goalie Tables") is an exceptional source for GSAx by goalie and season. I subscribe to this site, and I strongly encourage others to do the same. It goes way beyond just goalie stats in analyzing today's NHL.

That's it for bow. In subsequent articles I will analyze the best goaltender performances since 2008.



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