Dallas lost. Edmonton lost. New Jersey lost. Toronto lost. Colorado lost. Vegas lost. Six favorites entered Game 1 with high hopes. Six favorites exited in shock. Welcome to the 2023 Stanley Cup playoffs where the chaos has already begun.
It’s not chaotic for an underdog to get a win in the playoffs — we all know anyone can win on any night in this league — but six underdogs to start the playoffs certainly qualifies. Though there have been four instances in the salary-cap era where road teams won five of eight opening matchups (2010, 2015, 2017, 2021), this is the first time they’ve won six. You have to go back all the way to 2003 for the last time the road teams were this dominant to open the playoffs, when the lower seed went a shocking 7-1. Only two of those teams actually won their series, though.
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That’s the good news for New Jersey, Toronto, Colorado and Vegas — no series is won and lost after Game 1. There’s still plenty of series left. Dallas and Edmonton showed just that Wednesday night.
The bad news is that even if it worked out OK for the majority of teams in 2003, losing Game 1 in the salary-cap era has drastically lowered the odds for the home side. Since 2006 there have been 54 series where the home team lost the first game. Only 19, or 35 percent, came back to win the series. That’s not far off from the average series probability of 41 percent our model showed after Game 1 for the six higher seeds that lost. In other words, expect some upsets.
A lot depends on what happens in Game 2 and there is a slight rubber-band effect at play. Of the 54 series where the higher seed lost the opener, 32 went on to win Game 2 (59 percent) and it’s those series where a comeback has much more favorable odds. The home side has won 16 of 32 such series, evening the odds. That’s still not great considering most of those sides were likely much more heavily favored to start — but it’s better than 35 percent. The Stars and Oilers earned massive wins Wednesday in that regard.
It’s also better than what happens if the higher seed loses Games 1 and 2 at home. In those cases, the higher seed is 3-19, a 14 percent success rate. No pressure, Devils, Leafs, Avalanche and Golden Knights fans …
Updated 2023 Stanley Cup probabilities after Game 1 of the first roundhttps://t.co/X1h0Nx5xKG pic.twitter.com/zlx2Ml0Ipf
— dom 📈 (@domluszczyszyn) April 19, 2023
That pressure was already palpable at home for many of the higher seeds during Game 1. The Oilers blew a two-goal lead. The Devils admitted there were nerves at play and looked the part. The Golden Knights folded in the third period after struggling to do much through two periods. The Leafs looked like a team that knew this series was the most important in franchise history and was afraid of it.
It was a rough look all around for the home team after a rough season where home teams won their lowest percentage of games in 12 years. Has home ice become a disadvantage?
We’re going to answer that question immediately. No, home ice is not a disadvantage.
Eight games isn’t a whole lot to go off of and while home teams won much less often than usual in 2022-23, they still won 52.4 percent of the time.
But it is worth examining how large that advantage is and whether it’s an advantage that grows come playoff time.
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It may not feel like it after watching these playoffs so far, but in general playoff teams do usually perform better at home than they did during the regular season — though it does vary from season to season. Since 2008, home-ice advantage during the regular season has ranged anywhere between 52 to 57 percent. The playoffs are much more volatile, finishing anywhere between 45 percent (2012) and 69 percent (2013). That’s what happens when comparing a 90-game sample to a 1,200-game sample. The end result is playoff home teams winning 55.4 percent of the time since 2008, nearly one percentage point more than during the regular season at 54.6 percent.
The chart above really highlights the year-to-year volatility of playoff home-ice advantage and the wild swings from season to season. While the regular season is mostly steady, playoff home-ice advantage changes so drastically that it’s difficult to draw any meaningful conclusions. Some years it matters a lot. Some years it doesn’t at all. And it’s hard to predict whether it will or won’t in any given year — which can make forecasting what happens especially tricky. Last year, home teams won 61 percent of the time. This year is off to a rough start toward matching that.
There’s another added wrinkle to the home-ice effect come playoff time and that’s how far a goal goes toward contributing to a win. Goal differential and win percentage are tightly correlated in this sport, but what’s interesting is how the slope differs from the regular season to playoffs.
Based on the yearly relationship between goals percentage and win percentage a 52.5 percent goals percentage (roughly average for both playoffs and regular season) earns the home side a win percentage of 54.5 in the regular season and 54.9 percent in the playoffs. But every extra half percent of goals percentage adds 1.5 percentage points of win probability for regular-season hockey and just one percentage point in the playoffs.
What that means is if the home team earns 53 percent of the goals, theoretically they should see their win percentage jump to 56 percent. That’s almost exactly what we see in 2009, 2010, 2012, 2013, 2017 and 2018. In the playoffs from 2017 to 2021 the home team scored 53.2 percent of the goals … but only won 52 percent of games. During that span it peaked at 54.8 percent in a year where the home side scored 55.2 percent of the goals. Based on how goals and wins relate, home teams should’ve won 60 percent of the games that year or more. Even last year’s 60.7 percent win rate came off a high-water mark of 56.6 percent of the goals scored. Based on regular-season rates that should’ve meant winning 66.5 percent of the games, not 60.7.
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Maybe that’s just random variation — away teams have been much better in one-goal games than home teams since 2017. But it does suggest that while home ice is more valuable during the playoffs, it’s been a bit harder lately to collectively turn strong home performances into a deserving win percentage.
We’re 12 games into the playoffs with 70 or so still to go. The home teams will figure it out. The Stars and Oilers already have. There’s a good chance the Devils, Leafs, Avalanche and Golden Knights will too. Maybe they won’t! That’s hockey and part of the fun when it comes to playoff hockey specifically.
Playoff hockey is where chaos reigns supreme and we got an exciting early dose with six higher seeds facing immediate adversity. Time to see how they respond — and whether they can reignite the advantage that should come with having home ice.
Data via Natural Stat Trick
(Photo of the Dallas Stars in their Game 2 home win over the Minnesota Wild: Jerome Miron / USA Today
