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The Success Story of Thomas Greiss

The Islanders goalie is showing that last season was no fluke.

Tampa Bay Lightning v New York Islanders Photo by Bruce Bennett/Getty Images

Can they do it again?

It’s the question that reverberated throughout the summer about the Islanders, especially towards the team’s goalies given their Jennings Trophy victory. With Robin Lehner out and Semyon Varlamov in, much of the conversation was about a transformation in the “starter’s net.” No one talked much about Thomas Greiss, who has quietly played in 40 games in all but one season with the Islanders (2017-18).

It fits Greiss’ personality like a glove. By all accounts, he is an unassuming, even-keeled guy who just goes about doing his job well. And for the most part, the results have been there.

The Background

But as most things Islanders, a lot of their success is tied to anonymity. It’s almost been a hallmark of Greiss’ career on Long Island. Greiss signed in a backup role for two years before the 2015-16 season. He was fantastic in his first year and good in the second, prompting GM Garth Snow to sign him to a reasonable three-year extension.

The next year was a disaster for Greiss and the entire team, as the 2017-18 season came and went with turmoil both on and off the ice. Greiss’ finished with a career-low .892 save percentage. But in came Barry Trotz, and Greiss has picked up where he left off even better than before. He had a .927 save percentage last year and currently has a .930 save percentage in 12 games this year.

It’s gone mostly overlooked because Greiss has gone mostly overlooked. While Jaroslav Halak was injured, Greiss practically stole a playoff series (alongside John Tavares) against Florida. He was sat when Halak returned in the next round. While Robin Lehner was getting nominated for a Vezina Trophy, Greiss was putting up a .927 save percentage in almost 2,300 minutes. He played 36 minutes in relief during the 2018-19 playoffs.

That’s not necessarily a shot at anyone. Greiss has been somewhat typecasted as a “1B” (or even a backup) and the team has always had someone else. But this year has been different.

Barry Trotz has deployed Greiss and Varlamov in an even split. It’s gone so far to where they have alternated games through the first 22 games of the season. It’s a bit different from the routine for Greiss, who has typically played in streaks, but he’s handling it quite well by any discernible metric.

The Metrics

Let’s start with overall save percentage, where Greiss ranks third in the league of goalies who have played at least 500 minutes (old friend Robin Lehner currently ranks first at .938). His goals saved above average (GSAA) metric ranks 7th at +7.58, and his high danger save percentage in all situations ranks 12th at .849.

Using the invaluable Charting Hockey website by Sean Tierney, we can visualize Greiss’ success in a few ways.

Source: Charting Hockey

This first visualization is a heatmap of how Greiss ranks in available goaltending metrics, as displayed on The range goes from dark blue (good) to dark red (bad). Relative to his peers, Greiss grades out quite nicely here. In other words, no matter how it’s sliced Greiss is performing at an above-average level.

This is pretty high level, so let’s dive in a little further.

Source: Charting Hockey

This chart shows how goaltenders are performing relative to the types of shots they are receiving. To explain the axes on this chart, the x-axis shows the number of goals saved above average per hour. The y-axis shows the number of expected goals against per hour. So, the top half of the graph indicates “hard work,” while the bottom implies “easier work.” In other words, the level of defense that the goalie is playing behind matters.

We know the Islanders have a good defense, so it comes as no surprise that Greiss ranks in the bottom right quadrant. He is getting easier work than some of his counterparts, but his results have been quite good!

This can be seen in’s heat maps, which shows the Islanders as a strong defensive team while Greiss is in the net.

Source: HockeyViz

In the above, the blue spaces are areas where attempts are taken less frequently while the red areas show the opposite. Because we are looking at goalie defense, the red areas are “bad” for the Islanders. Even still, there’s a lot of predictability here - point shots are pretty common, and when teams are getting opportunities, they appear to be happening to Greiss’ right with a higher area of frequency. That may create a presumption for Greiss where he can “front” to where he expects plays to develop.

The Legacy

I had alluded to this in a previous ‘19 Isles Thoughts’ but there has to be some consideration for Greiss as one of the best goalies in team history. As mentioned, Greiss ranks fifth in team history in wins (94), eighth in games played (174 - he’ll likely be fifth by the end of the season), first in save percentage (.917 - though we know save percentages are higher post-1995), and fifth in Hockey-Reference Point Shares (31.6).

He’s been a stabilizing force for the second half of the 2010s, which has coincided with the teams’ greatest successes during these ten-years. It’s not anything to write home about, nor is Greiss the active cause for these wins, but he’s played a bigger role than what anyone may have anticipated upon his signing in 2015.

In The Athletic, Arthur Staple named Greiss on the Islanders All-Decade team. It’s practically impossible to disagree with that. And that’s why this is ultimately a great success story. Greiss was signed as a backup and wound up turning into the franchise’s most prolific goalie of the decade. Not bad.

So can they do it again? With another great performance out of Thomas Greiss, it’s getting hard to bet against them.

Metrics for this article were sourced by Natural Stat Trick, HockeyViz, and Hockey-Reference