...After tracking scoring chances, usually at the NHL level, since 1980, some interesting facts emerge. . . . The average number of scoring chances is about the same as when Roger and I coached in Buffalo, when anything under 15 chances against was acceptable..."
That's Ron Smith, currently a pro scout with the Carolina Hurricanes, discussing the post-lockout changes to the game and their true effect on the game. According to the article,...[Smith] began his NHL coaching career in 1980-81 as an assistant alongside the late -- and much loved -- Roger Neilson with the Buffalo Sabres."
As Vic Ferarri has written, Neilson was streamlining his reporting long before anyone else. We also know that Harry Sinden was tracking the equivalent of Corsi during the 1972 Summit Series. If Sinden was doing this in the Summit Series, we can also reasonably assume the Boston Bruins to be doing the same in the late 1960s.
All of this is significant because we know that NHL teams are teams are tracking advanced stats (AKA microstats, underlying stats) to some degree. The Sabres have been doing it since the days of Roger Neilson, same with the Rangers. The Sabres have been using Corsi since Jim Corsi has been there. Smith has been tracking scoring chances since 1980 and has worked for the Canucks, the Devils, the Rangers, and Hurricanes, so we know that those four teams are also tracking, at the very least, scoring chances.
The main criticism of advanced stats when analyzing players, games or teams is that they are "useless", as those "useless" stats often contradict what a critic believes he has seen on the ice. However, knowing that these teams are themselves using the same advanced stats means that those of us exploring and compiling these stats are, at the very least, on the right track.
*For a primer on the other stats mentioned here, please visit the always-lively Behind The Net Hockey.
Scoring Chances
Corsi
The latest statistical focus for the "Stat Geeks" has been tracking game-by-game scoring chances. The project was started by Dennis King who was interested in understanding who was driving the play in Edmonton, and streamlined by Vic Ferrari of timeonice.com with his magnificent tracking tools. Because the NHL does not track scoring chances as an official stat, a group of bloggers has taken it upon themselves to track scoring chances created on the ice through each game for a given team over the course of a season.
A scoring chance is defined as a clear play directed toward the opposing net from a dangerous scoring area - loosely defined as the top of the circle in and inside the faceoff dots (nicknamed the Home Plate), though sometimes slightly more generous than that depending on the amount of immediately-preceding puck movement or screens in front of the net. Blocked shots are generally not included but missed shots are. A player is awarded a scoring chance anytime he is on the ice and someone from either team has a chance to score. He is awarded a "chance for" if someone on his team has a chance to score and a "chance against" if the opposing team has a chance to score.
Seven teams are currently being tracked, the Oilers by Dennis King at MC79hockey.com, the Flames by Kent Wilson at Flames Nation, the Rangers by George Ays at Blueshirt Banter, the Panthers by Derek Zona at Litter Box Cats, the Capitals by Neil Greenberg at Russian Machine Never Breaks, the Canadiens by Olivier at En attendant les Nordiques, and the Leafs at Under the Helmet of Slava Duris.
Though chances are subjective, those tracking the chances attempt to hold to the above definition as closely as possible. When tracking chances for the Panthers, the Home Plate area is roughly defined as demonstrated in the picture below:
How do scoring chances correlate to Corsi and Fenwick, two of the primary microstats in the analysis toolkit? Vic Ferrari answered that in a post using Dennis' data. Corsi is a close estimation of zone time, or as everyone likes to say "puck possession". Scoring chances are generated through zone time, and goals come from scoring chances. In other words, when Corsi is spoken of as a measure of a player or team's effectiveness, there is math to back it up. Of course we have to look at those numbers in context, and when we don't we might say foolish things, but most people that use Corsi as a measuring stick use context.
The scoring chances project is significant in that it closes the loop on the data currently being used to analyze the game. The math behind the data has been validated, though NHL teams have known that for at least thirty years, possibly more. The conversation now must progress beyond defending the veracity of these statistics from the "saw him good" crowd and other critics to finding the next great innovation in statistics and analysis.
