Analytics with Alison: Improving Play in Net

Watching the Kraken of late, it feels like goaltending has become a strong part of overall play. After the 3-2 overtime loss to Boston on Thursday, Jordan Eberle described Philipp Grubauer's performance as "standing on his head." His head coach was equally complimentary.
"(Grubauer's) game tonight starting with the penalty kills, he was really sound (and) solid, (he had) a couple big saves," Dave Hakstol said. "The performance he had tonight…with that kind of a performance, our guys will fight hard for him."

So, is this surge in play in net real? Is it because of defensive play in front of the net? Are there specific changes either Seattle goaltender has made in how they approach a game or a shot? Are there tactical changes in how the Kraken is playing that are helping out their goalers?
Those are valid questions but also stories for a different day. Today, we want to simply see if the play in net has improved as much as our eyes tell us it has.
Let's dig in.
Of course, we look at as big of a sample size as possible to evaluate play, but it can also be valuable to look at trends within that sample itself.
The visual below courtesy of Evolving-Hockey.com shows all save percentages for Pacific Division teams (5-on-5 play; 5 game rolling average) for the season. The dashed line represents league average. Seattle's save percentage is bolded.

While we see that save percentage struggled early, it has been on the rebound ever since and at present, is falling more or less in line with that of other Pacific Division teams. To give perspective to this timeline, game 40 was Jan. 21 (at St. Louis) and game 50 was Feb. 17 (at Winnipeg).
Save percentage tells us one part of the story, specifically: of all the pucks fired on net, how many did a goaltender stop?
But that number doesn't tell us about the types of shots a goaltender faces. When we use "expected goals," we can evaluate the "shot quality" that is generated. So, let's look at the offense coming at Kraken goaltenders from the opponents they faced throughout the season.
The below visual from MoneyPuck.com shows us the kind of challenge that was in front of Seattle netminders (5-on-5 play, 5-game rolling average). The higher the data point, the more shot quality against the Kraken faced. Loosely translated, this shows how difficult a goaltender's task might be.

We see that particularly in February, the Kraken have had offensive challenges coming their way off opponents' sticks. Hakstol as well as Kraken players have talked about tightening up the defensive game, and they have greatly reduced rush chances against and made other strides protecting their own zone, but it's notable that some of the strongest goaltending of the Kraken season is coming in the face of some of the largest offensive pushes from opponents.
Let's put the two pieces together. The visual below (again from MoneyPuck.com, 5-on-5 play, 5-game rolling average), shows the differential of how many more goals against were scored compared to what the shot quality should have generated.

Again, we see a noticeable quieting in recent play.
One more way to look at goaltending performance? Sportlogiq tracks quite a few stats for goaltenders including quality starts (when a goaltender saves one goal - or more - than expected) and steals (when a goaltender's goals saved above expectations exceeds the goal differential in a game, minus empty net goals).
Thus far this season, the Kraken have nine total quality starts and three steals. Any time the Kraken have had a steal, they've won the game. They've also won six of the games that had quality starts. Five of those quality starts have come since Jan. 1, 2022.
Of course, Seattle goaltending has come from three players this season, so let's look specifically at the two who have played the most and examine what, if any, kind of uptick each has seen.
Phillip Grubauer
Getting the lion's share of ice time in 2022, Grubauer has played in 16 games in the new year. Looking at the ask of him, 12 of those games he was up against more shot quality than his season average (2.29 expected goals against), and he still beat his expected save percentage in half of those. Of the seven quality starts that Grubauer has had this season, five have come in 2022, and all three of his steals have occurred after Jan. 1.

Chris Driedger
Obviously having played more sparingly due to injury and COVID-19 protocols, Chris Driedger has played six games since Jan. 1. In those six matches, he has faced the two biggest workloads in terms of shot quality against (at Anaheim Feb. 11, at Vancouver Feb. 21) and in both of those matches he exceeded his expected save percentage and combined saved three goals against that should have been scored. He also had his only steal of the season, and one of his two quality starts on Jan. 13 versus St. Louis.

Of course, as with any player on any team, finding your best game and sustaining that play is key. But it's encouraging to see that right now the defensive side of the ice is showing improvement in keeping pucks out of the Kraken net relative to earlier in the season.