Photo credit: Thearon W. Henderson
They talk about them on the pre-game shows. Coaches lament about how many or how little they had. I write about them. They’re everywhere. Scoring chances are a new craze sweeping North America. By my count 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 Canadiens by Olivier at En attendant les Nordiques, the Leafs at Under the Helmet of Slava Duris and the Caps by yours truly. Find out why after the jump.
So we are all on the same page, let’s first define what I mean by a “scoring chance:”
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, 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.
For those of you that want something more visual, take a look at the diagram below. Shots from the green area are where I log scoring chances. I am going to further divide the rink so we can see just how more effective shots from the chance area are versus the rest of the ice. The light blue areas represent just outside of the scoring chance area, but still within the top of the circles. The darker blue areas extend from the top of the circles to the blue line and the purple area extends that further back to the red line (center ice).
I took location data for shots on goal and goals scored during even strength from 100 random NHL games that have been played this season, and then plotted them on the rink. Blue circle indicates a shot on goal, green circle a goal scored.
Here is the shot data by section:
|blue line to red line (purple)||2||152||1.30%|
|blue line to top of circles (blue)||89||2049||4.16%|
|left/right scoring area (light blue)||16||240||6.25%|
|Scoring Area (green)||411||2487||14.18%|
Far and away the best shots are those taken in the scoring chance area – more than double the next best position on the ice. Through 61 games, Washington has converted on 14.1% of their scoring chances, which appears to be close to league average.
Now you see why I pour over scoring chance data: it’s where the action is. A team’s ability to get scoring chances will impact its ability to win games. More chances = more goals = more wins. Another stat that is correlated to wins is Corsi, which measures the net difference between shots directed at the opposition’s goalie, including those missed or blocked. The higher the number, the better that player is at driving puck possession. Corsi is great, but I think scoring chances give a better idea of individual contribution. For example, suppose you have two players, each playing with similar quality of linemates (Corsi QoT), getting a similar number of offensive zone starts (OZone%) but generating very different Corsi numbers.
I think most would agree ‘Player A’ looks like the better bet. More net shots directed at the opposition’s goalie means greater puck possession. However, when we look at net 5v5 scoring chances per 60 minutes, we see a different picture.
‘Player B,’ despite being on the ice for less net shots directed at net, has been on the ice for more net scoring chances per 60 minutes and also sees a much higher percentage of shots as scoring chances. Remember, more chances mean more goals, which means more wins. Incidentally, ‘Player A’ is Mathieu Perreault and ‘Player B’ is Brooks Laich from this season.
So you see, we bloggers are clearly on to something — and it’s the same thing that NHL teams have tracked for some time.