One of the more advanced methods of analyzing a teams game nowadays is the use of Advanced Stats or as others may know it as; Analytics. First off, what exactly is analytics?
To be exact, analytics is the analysis of a teams characteristics through the use of statistics and other tools to gain a greater understanding of the effects of their performance.
In the NHL, we see many new-age management and development staff use this tool more and more because it gives us a real insight on a teams possession time with the puck, percentages off of common game situations, and more. It offers a perspective deeper into a teams game results, and is arguably a much better indicator of a teams success or the ability to maintain success rather, than other more generic statistics do. The most common advanced stat which I am sure many of you have heard of, being Corsi For. For those of you who do not know- here is how it begun, what it shows us, and why it is important. We will go into a deeper understanding of other advanced stats later on.
The formula of Corsi was pioneered by the Buffalo Sabres past General Manager, Darcy Rieger, who talked about his teams shot attempt differential, as an indicator of possession. The name actually stems from another member of the Buffalo Sabres staff- Jim Corsi. Shot Attempt differential is an excellent way to measure the approximate possession of a team- although there are some agreeable downfalls to Corsi…
Shot Attempts only occur in the offensive zone, so when a team has a shot attempt (shot on net, shot that misses the net, or a shot attempt that is blocked), it is because they are in the offensive zone. So if a teams differential is positive, that means they spent more time in the offensive zone than the defensive zone. For example, if a team has 36 shot attempts for, and 28 against, we use the Corsi Formula to figure out their Corsi For %. (CF%). Attempts for (36) divided by total events (64), leads the team to a 56.25% Corsi For %. Obviously if a team is over 50%, they are the team with the higher puck possession which statistically, the team with more puck possession usually has a higher percentage of winning the game.
Corsi is used for both a team as well as each individual player and believe it or not, Corsi has some value in determining a players contract as it is in the best interest of the team to acquire positive possession players. Individual Corsi is where some experts criticize the stat, for example, if a less-skilled player is on a line with two stronger players, his or her Corsi may be higher than it should be. Another example may be if a defenseman is on for 16 shot attempts for and only 9 against, but 7 out of the 9 against were a direct result of him or her turning the puck over, and none of the 16 for were as a result of his play- than it is a little bit of a misrepresentation of his/her puck possession. But… generally speaking, Corsi is a very good way to measure a player or teams puck possession numbers.
Another factor in Corsi numbers is Zone Starts. This is another stat that is tracked at high levels of hockey, because it plays a huge role in a players possession numbers. If a centreman has a 46% Corsi For rating, but starts 65% of his draws in the defensive zone, that has to be taken into consideration and truthfully, the player is actually doing well considering he is starting that many of his shifts 200 feet from the oppositions net. Zone Adjusted Corsi helps us pinpoint further into a players puck possession stats.
Keep in mind… Corsi is ONLY recorded at even strength. Shot Attempts do not count for you if they come on the Power Play, and on the flip side, do not count against you if you are killing a penalty, similar to +/-.
In closing, Corsi is a relevant way to predict the future of a player or team as well as reflect on the overall puck possession ability of either, without physically timing puck possession.