There is nothing quite like the stirring of a goalie controversy. Fans talk about aesthetics, the clutch gene and how much better off their squad would be if they just got [insert back-up with limited NHL experience here] or made a trade for [guy who played well in the playoffs that one time]. Hockey fans get very worked up about goaltending despite their goalie having a limited impact on their team's success or failure in a given season. Let's call it the Goaltending Limited Effects Theory.
As it stands now, save percentage is the most effective way to evaluate the performance of a goaltender (assuming the sample size is large enough). The numbers get a little more precise when you look only at even strength save percentage, as some guys get hosed by facing an inordinate number of shots on the man-advantage. So if we accept that save percentage is the best metric for goaltending performance evaluation, what about finding another way to express that number—say, in a way that better shows the value of a netminder?
The first step is finding the league-average save percentage in 5v5 situations. For the four years I looked at (2010-11 up to 2013-14) we're looking at a .922. So once we have that number, we subtract it from whatever save percentage the goaltender in question put up in any given year. For instance, Tuukka Rask put up the best EVSVP (even strength save percentage) in the NHL last year (.942) which makes him .020 better than the average goalie.
From there, we multiply that by the total number of shots Rask faced to get an idea of how many extra goals he prevented last year. That number is 1284, so the number of goals saved is 25.68. The wonderful Eric T. explained that six goals is equivalent to one win in the NHL, so just a little bit of dividing gives us the number of wins Rask was worth to the Bruins last year: 4.28. That is a lot. You can see last year's chart here.
Note that the win total is based on a hypothetical average goalie playing for the team in question. So Rask is worth 4.28 more wins than an average goalie (see: one with a .922 save percentage in even strength play) would have been for the Boston Bruins (because the total shots faced are specific to the team the goalie played for).
Rask was almost a full win better than Noted Bad Person Semyon Varlamov and was worth 7.01 more WAA (wins above average) than Noted Awful Goaltender Ondrej Pavelec who cost the Winnipeg Jets 2.73 wins last season. The chart includes goalies who played 30 games or more for brevity's sakes. Last year's numbers are good, but what about looking at who the most valuable netminders were over the past four years?
As you can see in the chart and graph above (click to enlarge), Henrik Lundqvist has (unsurprisingly) added the most value to his team over the past four years. He has been worth 7.85 WAA. That's it. Arguably the best goalie in hockey right now has added about two wins a year to the New York Rangers over the past four seasons. Of course, half the fun of these charts is looking to see who the worst and ... oh well hello there Martin Brodeur, how are you doing buddy?
Brodeur has been the least valuable goalie amongst goaltenders who have played in at least 90 games over the past four years and he has cost his team just 6.31 wins compared to an average goalie. That's bad, but nowhere near as detrimental as is conventionally thought. While the total wins added/subtracted is an interesting look, it obviously affects those who play a lot of games much more than those who play relatively few. So here's a graph sorted by Wins Added Per 60 Games (WPG60).
Rask has played 90 fewer games than Lundqvist which hurts him in the total wins added stat, but when the numbers are adjusted for a 60-game season, Rask pulls ahead. Lundqvist has been very consistent over the past four seasons while Rask has played the majority of his games the last two years and is leaning on an incredible 2013-14 season to boost his WPG60.
Looking at the top and bottom of these charts is great, but my primary interest is pointing out just how small the margins are when you get to the guys in the middle of the pack. For instance, James Reimer, the sacrificial lamb of the 2013-14 Maple Leafs season, was exactly league average last year. Antti Niemi had one of the worst seasons of his career and cost the San Jose Sharks precisely... 0.90 wins compared to the average goalie.
American Hero Jonathan Quick has led the Los Angeles Kings to 2.31 WAA over the past four seasons. Meanwhile, Red Wings fans can't handle Jimmy Howard holding the starting job despite being worth 3.37 WAA since 2010. The guy Wings' fans wanted to replace him with? Jonas Gustavsson—who has cost teams 4.93 wins compared to the average netminder in the past four years.
These numbers aren't all-knowing or all-telling, but they demonstrate what I think is a very valuable lesson for hockey fans: by and large, your goalie isn't the problem. A great goalie on a hot streak can help you overachieve (hello 2011-12 Mike Smith) and an awful one can really hurt your season (Ondrej Pavelec every year). But the Reimers, Howards and Niemis of the world? They aren't what's costing you a playoff spot. So how about more third-and-fourth-liner controversies instead next season?