Explaining Advanced Stats: Corsi Stats

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Mandatory Credit: Geoff Burke-USA TODAY Sports

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Many of our readers may be aware of the “advanced stats” paradigm shift taking place in hockey analysis recently with statistics like Corsi and Fenwick becoming more mainstream for armchair analysts like us here at Stars and Sticks. Still, these statistics are relatively new and can take some getting used to. In part two of our series explaining some of the statistics we use to analyze the Caps and the rest of the league, we cover the various Corsi stats, and how each of them can be a useful tool in breaking down the game.

What Exactly Is Corsi?

In order to understand all the different Corsi stats and why it’s such an effective tool, first one must understand what “Corsi” is. War On Ice defines Corsi as:

"Corsi%: The percentage of on-ice shot attempts (on goal, missed, or blocked) taken by the player’s team; also known as CF%"

The most important thing to remember is that Corsi is basically Fenwick plus shot attempts that are blocked.

The Different Corsi Stats

Here are the definitions for each Corsi stat, as defined by War On Ice:

"Corsi +/-: CorsiFor minus CorsiAgn; plus-minus for on-ice shot attemptsCorsi Rel%: The player’s on-ice Corsi% minus the player’s off-ice Corsi%; off-ice Corsi% is the percent of shot attempts taken by the player’s team when the player is not on the ice (but in games where the player is in the lineup); also known as CF Rel%CorsiAgn: The number of on-ice shot attempts (on goal, missed, or blocked) taken by the opposing teamCorsiAgn60: The rate of on-ice shot attempts (on goal, missed, or blocked) taken by the opposing team per 60 minutes of playCorsiFor: The number of on-ice shot attempts (on goal, missed, or blocked) taken by the player’s teamCorsiFor60: The rate of on-ice shot attempts (on goal, missed, or blocked) taken by the player’s team per 60 minutes of playCorsiPace60: The sum of CorsiFor60 and CorsiAgn60"

Corsi +/- is great for people who don’t like percentages and want simple numbers. Obviously, having a positive number in this category is a good thing. Negative numbers are usually bad. Corsi Rel% is a great tool to compare a team’s puck possession without a player on the ice. It tells you how good a teammate is at puck possession compared to the rest of his teammates. That’s very useful because sometimes, a player’s Corsi might look horrible, when in reality, it’s not horrible because most of his teammates had an even worse Corsi%.

CorsiAgn and CorsiAgn60 tells you how many shot attempts a team gives up per 60 minutes or how many shot attempts against his team that a player is on the ice for every 60 minutes. CorsiFor and CorsiFor60 tells you how many shot attempts a team has per 60 minutes or how many shot attempts for his team that a player is on the ice for every 60 minutes. CorsiPace60 tells you how many shot attempts (from both sides) a team sees per 60 minutes.

Apply Corsi!

Alright, let’s do some very simple math problems to apply what we have learned today. Player A is on the ice for 13 shot attempts and 7 shot attempts against. When he’s not on the ice, his team has 5 shot attempts for, and 15 shots against. Give his Corsi%, Corsi +/-, and Corsi Rel%, as well as his team’s Corsi%, Corsi +/-, CorsiAgn, CorsiAgn60, CorsiFor, CorsiFor60, and CorsiPace60.

Answer: Player A has a 65% Corsi% (13/20 = 65%), a +6 Corsi +/- (13-7=6), and a 40% Corsi Rel% (5/20 is 25%; 65%-25% = 40%). His team has a 45% Corsi% (13+5=18; 18/40 =.45 x 100 = 45%), a -4 Corsi +/-, a CorsiAgn of 22, a CorsiAgn60 of 66, a CorsiFor of 18, a CorsiFor60 of 54, and a CorsiPace60 of 120.

How Are The Caps At Corsi-ing?

The Capitals are currently 10th in the NHL with a 51.74% CF% at even strength. That tells me that they are darn good They are sixth in the NHL with a 53.74% CFClose% at even strength. Could be better, but it’s a huge improvement over last year when the Capitals were near the bottom of the list in each category.

NEXT: Zone Start Percentage