Carolina Hurricanes

Hockey analytics: Gauging the impact of injuries

Brandon Dubinsky had 16 goals and a career-high 34 assists last season.
Brandon Dubinsky had 16 goals and a career-high 34 assists last season. AP

Ian Cooper writes for The Department of Hockey Analytics, based in Toronto, which examines NHL statistics to find trends within the game.

Few things can change a team’s fortunes as suddenly as an injury. But when that key player goes down, how can you tell how bad it will be?

Most commentators tend to focus on a player’s offensive production. So, for example, when Tampa Bay’s Steven Stamkos went down last season, we heard a lot about the loss of a former 60-goal scorer and a favorite to win the Rocket Richard trophy.

When we’re talking about a player who will get you 45 goals in an “off” year and 60 in a good one that’s probably good enough. Very few people in the league, let alone on Tampa Bay, can replace that production.

But if we’re talking about Philadelphia’s Vincent Lecavalier’s current injury vs. the Hurricanes’ Jordan Staal’s, who will be missed more by his team?

Lecavalier had 37 points in 69 games last season; Staal had 40 in 82. On a point-per-game basis, Lecavalier gets the edge but not by enough to make you sure either way.

What we do know for sure is that both logged significant ice time last season (Staal averaged 18:56, Lecavalier averaged 15:11), and someone will have to carry those minutes.

If you want to know what each team has available to fill that void, a handy statistic called Corsi Rel% will help you figure that out.

There are a couple of variations on how Corsi Rel% is calculated, but I prefer the simple version used by war-on-ice.com, which takes an individual player’s Corsi For percentage (measured as the number of shot attempts his team took while he was on the ice as a percentage of all shots taken by both teams) and then subtracts the rest of his team’s Corsi For percentage when he’s not on the ice.

Corsi Rel% is really useful in figuring out how much an injury is going to cost a team because it directly compares the injured player with the teammates who are available to replace him.

Take the example of elite shutdown defenseman Marc-Edouard Vlasic of the San Jose Sharks. Vlasic’s Corsi Rel% was 7.12 last season, meaning when Vlasic wasn’t on the ice during 5-on-5 play, the San Jose Sharks went from a possession juggernaut (Corsi For percentage of 58.17) to mediocre (Corsi For percentage of 51.05).

Vlasic may have ceded the limelight to scorers Joe Thornton, Patrick Marleau and Joe Pavelski, but on a team that was fifth in goals for last season (249), Vlasic’s extraordinary defensive abilities made him the one player the Sharks couldn’t afford to lose.

When Vlasic went down in the first period of Game 5 of their playoff series against the Los Angeles Kings, San Jose ended up dropping that game and the next two.

The Sharks minus Vlasic simply weren’t good enough to compete with a Kings team that led the league during the regular season with a Corsi For percentage of 56.80.

The table shows which teams are currently missing key players for what will likely be more than several games and their Corsi Rel% from 2013-14. We’ve also included each player’s rank among all of his teammates at his position (i.e. forward or defenseman) and average time on ice to give a more granular picture of what the loss will cost.

As one would expect, the Red Wings will feel a fair bit of pain without Pavel Datsyuk in the lineup, but because Detroit enjoys some depth at forward and is generally a good possession team, life without Datsyuk won’t be quite as awful as it could be if a weaker team lost a player of Datsyuk’s abilities.

Meanwhile, although Staal had fewer points per game than Lecavalier last season, his Corsi Rel% of 5.25 tells us he’s an important part of the Hurricanes and will be missed; whereas, Lecavalier’s horrendous Corsi Rel% of -5.15 suggests Flyers fans probably aren’t sending him any “get well soon” cards.

Corsi Rel% doesn’t give us the whole picture of a player’s value to his team. Other factors, such as quality of opponents, zone starts and teammates help focus the conversation further (we’ll be talking about those in future columns). But it’s an excellent starting point to determining how much a player will be missed if he is injured.

The Department of Hockey Analytics employs advanced statistical methods and innovative approaches to better understand the game of hockey. Its three founders are Ian Cooper, a lawyer, former player agent and Wharton Business School graduate; Dr. Phil Curry, a professor of economics at the University of Waterloo; and IJay Palansky, a litigator at the law firm of Armstrong Teasdale, former high-stakes professional poker player, and Harvard Law School graduate. Please visit us online at www.depthockeyanalytics.com

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