What is expected goal differential? The advanced stat sweeping through the hockey world

Stats and analytics are becoming a major part in how sports teams analyze success. 

Hockey is not different. There are now ways to track the quality of a shot, the impact of a player’s defense on a team’s total wins and so many other concepts that might be confusing to the average fan. 

One of those is expected goal differential. The statistic is becoming a bigger part of diving into a team’s offensive and defensive output and predicting how it will impact the club’s success. It was discussed frequently at the trade deadline, looking at how one player’s addition or subtraction affected the team’s expected goal differential. 

But what exactly is this statistic? Sporting News helps break down one of the more popular tools used in the analytics world. 

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What is expected goal differential in the NHL?

While expected goal differential might sound difficult to understand, it isn’t as complex as you think. 

Expected goal differential is calculated by subtracting a team’s expected goals against from their expected goals for. The way those two numbers are calculated are a bit complex, but this is how Kraken’s analyst Alison Lukan describes expected goals for:

“In the broadest sense, expected goals (xG) is a measure that seeks to address the concern that not all shots are created equal. xG considers a variety of factors and then mathematically assigns a value to each shot attempt that represents the probability of that shot becoming a goal. That value can come in one of two forms: it can be a percentage — which directly represents how likely a goal was to follow; or it can be a straight value which factors in probability. Terms like “expected goals” and xG can feel clunky, so I like to call this measure simply ‘shot quality.'”

Basically, there are statistics that look beyond just shots taken and shots allowed and really analyze the quality of chances from those shots and how many goals a team is expected to give up or score. From those two statistics, the expected goal differential can be concluded. 

The benefit with this stat is that you can also use it in multiple scenarios. You can look at a team’s expected goal differential at 5 on 5, 5 on 4, 4 on 4 or all situations. 

Here is a graph of the expected goal differential of all 32 NHL teams in all situations as of March 27, thanks to MoneyPuck. 

Who has the best expected goal differential in the NHL?

In order to be one of the best teams in the league, you need to score more often than you allow goals. 

So it’s not a shock to see that the clubs at the top of the NHL standings are the same ones topping the leaderboard for expected goal differential. 

Here is a look at the top 10 teams in terms of expected goal differential. 

Who has the worst expected goal differential in the NHL?

It shouldn’t come as a surprise that the teams with the worst goal differential are those that sit at the bottom of the standings. 

When you are expected to give up more goals than you score, you can’t win many games. And that is exactly the case with these teams. 

Here are the bottom 10 teams in terms of expected goal differential. 

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