## Underlying Metrics Are Stupid... Stupid Easy

Bruce Fedyck-USA TODAY Sports

Showing how hockey statistics are easy to understand and use for both fan and media alike.

There are those that communicate with members of Arctic Ice Hockey often but openly mention that they do not understand shot metrics. Usually, they cite things like stupidity, age, or being too old school as the reasoning. There are also media members who state that the numbers in underlying analytics are too complex for use with the general public.

In high school chemistry, students are taught something called "the Bohr model". Without going in much detail, the Bohr model was a simple hypothesis on how atoms are framed. The hypothesis though turned out to be overly simplistic. Atoms are far more complex; yet the Bohr model is still taught in high school. The reason it is still taught is because -despite its flaws- it works. The model explains things sufficiently well enough that you can learn the basics of chemistry without any issues.

This article covers hockey statistics in much the same way. This is not an in-depth introduction to underlying numbers; you can get enough of that here if you want. It is however a way to show how hockey statistics represent important factors that have always been part of the game.

Welcome to hockey statistics for idiots (insert the yellow and black cover here).

### Corsi is all about possession

#### Basically:

When you see the word Corsi, think puck possession. Corsi measures all shot attempts for either a team or when a particular player is on the ice. Due to Corsi being measured in shot attempts, the number does not describe much of "dead zone possession" but the difference in the attack zone by two teams. Statisticians commonly display Corsi in a percentage, where most of the NHL falls between 40-60%.

#### Punchline:

When you see a number close to 40% for Corsi, think of a player or team being hemmed in their own zone a lot; a number close to 60% describes the opposite.

#### A wee bit more:

Corsi shows you which players are more likely to outscore than be outscored, which is why you should care about the number. For more on Corsi, check this article.

### Fenwick is all about scoring chances

#### Basically:

When you see the word Fenwick, think scoring chances. Fenwick measures shot attempts for either a team or when a particular player is on the ice, but removes blocked shots. Now obviously not every non-blocked shot attempt will be a scoring chance; however, the teams that lead in one, tend to lead in the other. Statisticians commonly display Fenwick in a percentage, where most of the NHL falls between 40-60%, just like Corsi.

#### Punchline:

When you see a number close to 40% for Fenwick, think of a player or team being outchanced a lot; a number close to 60% describes the opposite.

#### A wee bit more:

Fenwick is a bit smaller in sample size, so generally speaking Corsi is used more often for smaller samples like a single game or player. In those cases, possession and scoring chances are a little more synonymous. For more on Corsi vs Fenwick, check this article.

### On-ice shooting percentage, on-ice save percentage, and PDO are all about bounces

#### Basically:

On-ice shooting percentage shows what percentage of shots are going into their opponents net when a player is on the ice. On-ice save percentage shows what percentage of shots are not going into their own net when a player is on the ice. PDO is the two being combined. When you see these numbers think about bounces. While talent, effort, and skill drive results, sometimes a player might get a few more or less bounces than the other guy, or what the player had previously and likely to receive in the future.

#### Punchline:

If a player has an on-ice shooting percentage substantially lower (or higher) than he's accustomed to in the past, there is a chance his point production may be a bit lower (or higher) due to bounces. If a player has a PDO substantially lower (or higher) than he's accustomed to in the past, there is a chance that his goal differential (plus/minus for 5v5 only) may be a bit lower (or higher) due to bounces.

#### A wee bit more:

Playing with better linemates like Blake Wheeler over Chris Thorburn may raise your on-ice sh%, just like playing with Ondrej Pavelec instead of Tuukka Rask may lower your on-ice sv%; however, this would take a large sample to confidently lose the white noise (bounces) from the numbers. For an interesting article on percentages and shot quality, check this article.

### Offensive zone starts, quality of teammate and quality of opponent is all about context

#### Basically:

A lot of the people who complain about hockey statistics say it is because they lack context. These statistics are all about adding that context. Offensive zone starts show how often a player is starting their shift in the offensive zone versus the defensive zone. Quality of teammate shows how linemates may have an influence on the results. Quality of opposition shows how line matching may have an influence on the results.

#### Punchline:

The harder the players deployment, the lower the expected results should be and therefore should be taken into account. More defensive zone deployment, weaker linemates and tougher linematching will make life difficult for a player to do well.

#### A wee bit more:

Not all contextual nuances are created equal. It seems that zone deployment is the strongest, then linemates, and then linematches. There is still a lot more studying going on in this area.

### A few final words...

Hockey statistics for the most part represent things hockey players and media talk about all the time: possession, chances, bounces, and usage. The difference is they put a number to the factors, allowing for comparisons to be made.

This article was made for the common fan to show that anyone can understand these statistics. They are not "advanced" stats, so do not fret.

It was also made for the common media member, to show that anyone can write about statistics, even without using the numbers specifically. A media person can mention possession, chances, bounces, and usage without ever having to use specifically Corsi, Fenwick, etc.

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