User:Tneedleman/Corsi (statistic)

Individual players tracked by Corsi stats are used to help decide when you should put a player on the ice depending on if your are trailing, winning or tied. The idea behind this method is the more attempts on goal means the more offensive zone time you are getting meaning more chances for a shot. If you have a poor Corsi percentage this means the opposing team is having the upper advantage in the game. These stats are broken down into two categories. The first being a Corsi for Event and a Corsi Against Event, the first meaning the shots attempted by your team, and the second being the shots against your team. The number is calculated when both teams are at even strength by taking the shot attempts and dividing that number of shots by the opponent. You take each individuals Corsi percentage and that is how you discover your teams. A good Corsi percentage for a team is anything over 50% while anything under is considered poor and therefor that team is getting outplayed. In 2016 the Penguins who ended up winning the Stanley Cup ended up with a 52.8 percent Corsi percentage which was the second highest in the league. In 2016 8 of the top 10 teams for Corsi percentage qualified for the playoffs. Every single shot is calculated in the Corsi method, these shots would include shots on net, shots that miss the goal, shots that turn into goals and shots that are blocked or deflected. The Corsi method is extremely valuable as it can be broken down to different aspects of the game. The Corsi method is very similar to the Fenwick method, however the Fenwick method does not include shots that are block or deflected by your own team or the opposing team.

The corsi statistic is an advanced statistic used in the National Hockey League. Corsi is the total shots at the net for and against at even strength. It’s often expressed as either a differential, like plus/minus, or a percentage. The corsi statistic is a proxy measure of offensive zone possession.

History[edit]
The corsi statistic is named after Jim Corsi, but he is not the one to create it. An outside-the-box thinker, Corsi was trying to measure just how busy his goalies were in a game. He didn’t believe the simple shots-against total — usually around 30 a game — was totally reflective of just how busy a goalie was. And since it’s up to the goalie coach to ensure the goalie is in shape, it was up to Corsi to find out how much workout time goalies needed between games. Corsi stats that “Another fellow took my stats and started applying it to players to find out what their contribution was overall, on both sides of the puck, and voila, the Corsi stat came out.”

The corsi statistic was named in 2004 by Tim Barnes, a engineer turned financial analysts from Canada but currently resides in Chicago. Barnes help develop, popularize, and spread the stat. Barnes did this by blogging anonymously - and more famously - under the pseudonym, Vic Ferrari. Barnes, with the help of other blogger, Gabriel Desjardins, ideas took root when many NHL fans were unsatisfied with the plus-minus stat, in large part because they believed goals were akin to random events. There are more shots and shot attempts in a game than goals and shots on goal, meaning the larger sample size of Corsi events is more reflective of a player’s performance than whether a player is on the ice for an unlucky bounce. Barnes turns out to be, the other fellow.

Relevance[edit]
Corsi is a proxy measure for offensive zone possession. Players and teams with positive Corsi rates tend to spend more time in the offensive zone at five-on-five, something that’s predictive of success over the long-term. In general, the higher the corsi differential or ratio, the more dominant the team or player. At the same time, the blogosphere was trying to find out what teams were best at puck possession. The NHL dropped time of possession as a stat in 2002. So bloggers turned to Corsi as its proxy, figuring if one team shot the puck more than the other team, it meant one team controlled the puck more than the other team. By measuring the various shots in 5-on-5 situations — like plus-minus — it puts all players on a level playing field. The stars don’t get the advantage that power plays give them. The grinders aren’t hurt by their time killing penalties. They can be measured with various linemates and against strong or weak opposition.

Starting with Corsi, there are two kinds of Events: a Corsi For Event and a Corsi Against Event. Again, despite the names, those are quite simple: a Corsi For Event is a shot attempt by your team, a Corsi Against Event is a shot attempt by your opponent. Corsi Events include all shot attempts, regardless of whether they're saved, blocked, off-target, or scored.