Win the goaltending battle, win the playoff game

We are eight games into the Stanley Cup Playoffs, and the overarching theme from the opening two nights was simple: goaltending won the day.

Goaltenders have borne the brunt of the NHL’s heightened scoring environment, persistently under siege for the past few seasons. At last check, towards the end of the regular season, we saw goaltenders capitulating in remarkable fashion, stopping under 90 per cent of shots league-wide. So yes, goaltenders have been having a tough time for a while now.

But observable struggles league-wide do not diminish the sheer importance of receiving quality goaltending, especially on a relative basis. We may have calibrated our understanding of what is considered elite puck stopping to the downside in 2023, but we also know how important it is to have a goaltending advantage in a given game. These are mutually exclusive points.

Just look at what happened over the first eight games. This is, by and large, still a league heavily driven by goaltending performance. The teams that saw their goaltenders erasing critical scoring chances in the opening game won; the teams that saw goaltenders either outplayed or persistently under siege lost. It is that simple.

Consider the below table, which shows the opening two nights for each series and how each goaltender fared. Only one team (the Toronto Maple Leafs, who mercifully pulled Ilya Samsonov after his Game 1 shelling) used multiple goaltenders.

Here’s how those games played out:

Score effects have a considerable impact on any game and that’s true in the playoffs – teams trailing are inclined to play more aggressively to generate higher volumes of scoring chances, while teams leading are inclined to play more conservatively, protecting the net in exchange for disadvantageous scoring chance volumes. But look at how many of these teams – including a handful that who won by multiple goals – carried negative expected goal rates over the course of the game, and contrast that with the final score. A marked difference.

How do we explain it? Beyond score effects, a theme in many of these games – whether you were watching the games in real time or going through the data post game – was one goaltender considerably outplaying another.

Let’s look again at these eight games, but study it through the lens of goals saved versus expectations, which measures a goaltender’s relative performance based on the shot profile he faced over the course of the night. That shot profile includes both shot volume against, and the probability of those shots finding the back of the net.

There is an easy argument to make that five goaltenders – Linus Ullmark, Antti Raanta, Filip Gustavsson, Joonas Korpisalo, and Philipp Grubauer – were the primary reason their team is up a game in the series, having erased more than a full goal versus expected in their debuts. You could also argue two goaltenders blew up their team’s chances of having any chance of winning, that including Vitek Vanecek in New Jersey and the Samsonov/Joseph Woll duo in Toronto.

That leaves us with the Connor Hellebuyck and Laurent Brossoit matchup, which is probably the most one-sided goaltending matchup you can find in the first round. Hellebuyck was quality, Brossoit was not, and the delta between the two was more than a pair of goals.

We well know that goaltenders can have outsized impacts on single-game outcomes. That’s been true for as long as the NHL has been in existence. But it’s not often we see such significant, one-sided directionality like this. It’s not lost on me that many of the goaltenders who won their respective matchups in the opening frame, save for perhaps Raanta in Carolina and Grubauer in Seattle, have stronger relative track records of success.

The beauty of the Stanley Cup Playoffs is things can change on a dime. But after the opening pair of nights, my read is that the teams that have goaltending questions aren’t breathing easy right now. 

Data via Natural Stat Trick, NHL.com, Evolving Hockey