The wave of advanced analytics has hit the hockey world.
While some organizations have been using advanced metrics for years, many do not. As the public has been slowly introduced to metrics such as Corsi and Fenwick, confusion abounds about what those numbers really mean and how they are calculated.
Fear no more as a comprehensive guide to advanced hockey stats has finally been published: Rob Vollman's Hockey Abstract.
Vollman was a founding writer for Hockey Prospectus and is best known for his player usage charts. He has contributed to ESPN as well as co-authoring three books: Hockey Prospectus 2010-2011, Hockey Prospectus 2011-2012 and Hockey Prospectus 2012-2013.
Not only does Vollman discuss the various types of advanced analytics used in hockey, he also introduces the book by explaining the purpose for writing it in the first place. (For baseball fans, he compares Hockey Abstract to Bill James' Baseball Abstract, a book that helped kick off the advanced analytics movement in baseball).
It takes only two pages to find out Hockey Abstract is different from a typical statistical analysis piece. Vollman wants Hockey Abstract to be, "a fun and informative book, not a text book." His conversational tone and writing style make the reader feel comfortable and at ease despite the amount of numbers involved.
Vollman answers all the typical questions using these statistics, including:
- Who is the best offensive player?
- Who is the best defensive defenseman?
- Who is the best defensive forward?
- Who is the best playmaker?
- Who is the best goalie?
- Who is the best coach?
The theme of Hockey Abstract, and advanced hockey metrics in general, is puck possession. The author equates puck possession to on-base percentage in baseball by describing both as, "a recordable skill that is closely related to winning but is nevertheless undervalued." Vollman explains how metrics like Corsi and Fenwick are used as proxies for puck possession.
Hockey Abstract is a guide to how to understand and utilize advanced hockey statistics in terms of getting the bigger picture of what is happening on the ice. These methods are not intended to replace the value of traditional stats, like goals and points, but are another tool one can utilize when evaluating a player. Defensive prowess becomes more quantifiable than +/- and it becomes easier to assess the entire player pool against itself instead of by position.
A typical chapter in the book consists of a brief introduction to whatever metric the following chapter is about, followed by a note that a more thorough explanation of the topic will have its own separate chapter later in the book. This is a great feature for someone with moderate to advanced knowledge of hockey's advanced analytics, but could be an issue for someone with little to no prior knowledge of the subject. However, Vollman puts the complicated and fuzzy world of advanced stats into layman's terms that make reading about them easier and more enjoyable.
A major plus to the book's appeal and credibility is the inclusion of sources from around the hockey world that are known for their research on parts of hockey analytics. People like: Eric Tulsky, Vic Ferrari and Gabriel Desjardins. With referencing the work (either directly in the writing or in footnotes) of the preceding names, Vollman adds even more credibility to the book. This is not one man's work being forced upon the reader, it's a collection of information gathered through many sources over several years.
Arguably the most enjoyable way by which to analyze hockey players is usage charts, Vollman's specialty. The middle of the book contains usage charts for every team, combining the last five seasons. For those who have never seen or used a player usage chart before, the array of various circle sizes, locations and colors are visually pleasing while being informative. For visual learners (and everybody really) these charts explain which players play in which scenarios (commonly broken down to quadrants of shut down, two-way, sheltered and less sheltered) and how successful they were in directing shots toward the other net as opposed to their own.
Vollman typically uses a five-year cumulative window when compiling stats for his book. While that eliminates some of the effects of a small sample size, the lists include players who are no longer active and teams that have changed strategies and success levels. The Phoenix Coyotes are an example of the latter.
By using data that includes the Wayne Gretzky era, Coyotes fans may get a partially skewed vision of the team's current success in relation to the six-year window (2007-2008 to 2012-2013) used for team evaluation in the book.
While the data ranges are clearly labeled, readers must pay special attention to those ranges, as not every chart uses the same time frame.
All in all, Hockey Abstract is a very gratifying and informative read. The future is here, and with Vollman's book, there are no more excuses as to why you can't be informed about advanced hockey analytics; whether you agree with them or not.
Disclaimer: Five for Howling was provided a reviewer copy of the PDF edition by the author.