Editors Note: Derek has been tracking scoring chances for each San Jose game throughout the season on his blog "The Neutral". It's a great read and we'll be featuring some of his pieces here at Fear the Fin. Enjoy!
As part of the Scoring Chance Project, I've been tracking scoring chances for the Sharks on a game-by-game basis this season over at The Neutral. With the Sharks set to begin their third month of action tomorrow evening against Montreal, now seemed like an appropriate time for me to share the results of the project so far with the Fear the Fin community.
First of all, the purpose of the project is to provide additional data about how the team as a whole, as well as individual players, performed in both single games and, eventually, over the course of the entire season. As we know, the final score can sometimes fail to tell the entire story. Teams can dominate their opponents only to end up losing the game due to a bounce or two going against them. That's hockey and it's why the advanced stats crowd in the sport have long been proponents of metrics like Corsi and Fenwick which evaluate teams based on shot differential instead of goal differential.
The most common criticism of those numbers is that they ignore the quality of shots that teams are taking. Tracking scoring chances is a way of verifying claims about an individual team's propensity for registering or allowing high quality shots as well as determining which players are most effective at generating and suppressing these chances. Another frequent retort to hockey sabermetrics is that those in support of them should try "watching the game" and, of course, all the data I've collected here is from watching Sharks games this season and using the incomparable Vic Ferrari's chance-counting script.Scoring chance zone
I should probably start with a concrete definition of what a "scoring chance" is. A scoring chance is recorded when a player on either team directs a shot towards the net from the "home plate" area seen here, courtesy of Flames Nation:
Missed shots count but blocked shots do not (here's why). The area closely resembles this heat map by Ken Krzywicki via Russian Machine Never Breaks that details the likelihood of a shot directed at the net from a certain location on the ice ending up in the back of the net. I'm sometimes more generous in recording a shot as a chance if it's the result of a series of cross-ice passes that presumably force the goaltender to move laterally. When a chance is recorded, every player on the ice whose team the chance was in favor of is attributed a "chance for" while the players on the other team are given a "chance against."
Obviously not every scoring chance results in a goal but also not every goal is considered a scoring chance. Bobby Ryan putting the puck in his own net on this play was entertaining but wasn't counted as a chance. Neither was Joe Thornton banking the puck in off Jonathan Quick's glove from behind the net. None of the Canucks' three goals in their recent visit to San Jose were recorded as scoring chances either, all of them coming from outside the designated area.
Overall Sharks scoring chances
|Total SCF||Total SCA||Total SCF%||ES SCF||ES SCA||ES SCF%||PP SCF||SH SCA||SH SCF||PK SCA|
Definitions are probably in order here. SCF and SCA stand for scoring chances for and scoring chances against, respectively, which are then broken down by game state including even strength, power play and penalty kill with SH SCA representing chances recorded by penalty killers against the Sharks' power play and SH SCF the chances Sharks penalty killers recorded during the opponent's power play.
Individual forward on-ice even-strength scoring chances
|Player||ES TOI||ES SCF||ES SCA||ES SCF%||QoC Rank||SCF/15||SCA/15||ZSD|
Time for more defintions. ES SCF and ES SCA refer to the number of scoring chances that went for and against the Sharks, respectively, in even-strength situations when each player was on the ice. QoC Rank, courtesy of the indispensable behindthenet.ca, is each Sharks forward's rank from 1-15 of the average Relative Corsi of opponents that player faced, weighted by head-to-head ice time. In English, it's a barometer of how good the opposing players each Sharks forward faced generally were. SCF/15 and SCA/15 are the on-ice chances for and against that each San Jose forward averaged per 15 minutes of even-strength ice time. ZSD is the number of times each individual forward has started a shift in the offensive zone this season subtracted from the number of times that forward has started a shift in the defensive zone. More on that one later.
So obviously the fact that players like Desjardins and A. Murray are near the top of the list in SCF% is going to raise a few eyebrows although it's at least comforting to know that the fourth line is not an area of concern for the Sharks. Thanks to George Ays who tracks chances for the New York Rangers, there's a way of adjusting players' scoring chance numbers so that players aren't excessively rewarded or penalized for favorable or unfavorable zone starts. Using scoring chance data from last season, Ays was able to estimate that each additional start in the offensive zone was worth about 0.425 scoring chances. For example, Andrew Murray has been on the ice for 32 chances for and 21 against for a SCF +/- of 9. But he's also started 21 more shifts in the offensive zone than his own end, so 9+(0.425*-21) gives us an adjusted +/- of 2.075. So by correcting each player's raw SCF +/- using this information, we get a table that looks like this:
|Player||Adjusted SCF +/-|
That looks a lot more reasonable although there's still a lot of interesting and unexpected stuff to parse through, not the least of which is the fact that Torrey Mitchell still leads the team's forwards in scoring chance differential. He isn't exactly known as an offensive weapon (unless tacos are on the line, apparently). Some of that is the fact that Mitchell has had the good fortune to play with Clowe and Marleau recently but it isn't just luck; Mitchell's speed and forechecking ability, though far from consistent, have been the direct cause of a lot of those chances. I wouldn't expect Torrey to stay atop the team in this category for much longer, just as I wouldn't expect Havlat to remain in the basement, but kudos to a great first quarter for #17 as the coaching staff's decision to trust him with second line minutes when looking to spread out the offense by moving Havlat to the third unit appears to have been more than justified.
Individual defenseman on-ice even-strength scoring chances
|Player||ES TOI||ES SCF||ES SCA||ES SCF%||QoC Rank||SCF/15||SCA/15||ZSD||Adj. +/-|
I included the zone start-adjusted +/- in the final column for the d-men. I would think this list is a lot less surprising for most Sharks fans than the forward summary.
Individual on-ice power play chances for
|Player||PP TOI||PP SCF||PP SCF/2|
This one's sorted by PP SCF/2, which is the same idea as SCF/15 but tracking power play chances for every 2 minutes of time with the man advantage instead of even-strength chances per 15.
Individual on-ice shorthanded chances against
|Player||SH TOI||SH SCA||SH SCA/2|
Player-attributed scoring chances
I don't know how many people actually made it through all of that but, if you did, I hope you found the data useful. I'm planning on continuing to track chances at least through the end of the season so feel free to stop by The Neutral to check out the game-by-game numbers which I usually update fairly soon after the final horn. If you have any questions or suggestions by all means drop me a line in the comments. Thanks for reading.
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