GSAA is a stat that measures a goaltender's performance relative to the average goaltender in the NHL. It takes into account the number of goals a goalie has allowed, the quality of the shots he has faced, and the save percentage of other goalies in the league.

To calculate GSAA, the NHL first calculates the expected goals against (xGA) for each shot. xGA is a stat that measures the likelihood of a shot going in based on factors such as the location of the shot, the type of shot, and the shooter.

The NHL then compares a goalie's actual goals against (GA) to his xGA. If a goalie has allowed more goals than expected, his GSAA will be negative. If he has allowed fewer goals than expected, his GSAA will be positive.

GSAA is a valuable stat because it allows teams to compare the performance of different goalies. It can also be used to identify goalies who are playing well above or below expectations.

Here are some of the benefits of using GSAA:

* It is a more accurate measure of a goalie's performance than save percentage.

* It takes into account the quality of the shots a goalie has faced.

* It is comparable across different teams and leagues.

* It can be used to identify goalies who are playing well above or below expectations.

GSAA is still a relatively new statistic, but it is quickly becoming one of the most important stats in hockey. It is a valuable tool for teams, scouts, and fans alike.