Puck Possessed Issue 9: shot attempts and scoring chances
In issue 2 I talked a bit about shot attempts, but the current issue goes deeper, and also looks at, and explains, scoring chances.
The first page of the issue is about shot quality and quality. Is it better to show often or pick and choose only those locations that have a higher statistical chance of scoring? A table compares how teams rank for both shot attempts (abbreviated as SA, not to be confused with shots against) and Goals as a ratio of SAs. These two rankings are then combined, and not to anyone’s surprise, the Lighting come out on top. They still shoot often (ranked 9th out of 31) but also convert SAs into goals most of all teams.
The first bar chart show the same SAs but per event type as tracked by the NHL (blocked, missed and saved shots, and goals). The scatter chart shows the same data again, but also shows how the teams compare with the league averages. It is typically the case that teams that are far from the average will get back closer to the average over time, which could indicate a decline in goal conversion rates for teams like Lightning, Blue Jackets, and Penguins, and the opposite for teams like Coyotes, Kings and Canes. With the Canes shooting well above the league average number of SAs an improvement in Goals% can make them a team to keep an eye on.
The second page goes a bit deeper by looking at where shot attempts are taken from. The assumption is still that just shooting more does not necessarily lead to more goals. Now we look at the percentage of SAs shot from High Danger areas, further explained on the dashboard. Lastly the relationship between goals per shot attempts, and high danger shot attempts as compared to all shot attempts. Apparently the Islanders take a lot of shot attempts from high danger areas and also do a good job converting them into goals. However, unfortunately for them they produce one of the lowest numbers of shot attempts in the league. To see where they shoot from, click on any team icon and see their shot charts updated.
This is as good a point as anywhere to mention this issue strictly looks at shot attempts for, in other words shots etc. taken by the team of interest. Shot against are ignored here. So teams that do well in these charts and tables don’t always do well in the NHL, as they get more shot attempts / goals against than they do themselves.
Page 3 further explains the concept of scoring chances based on work from War On Ice and Natural Stat Trick and compares shot attempts from the offensive zone to medium and high danger scoring chances. As you will read, this goes well beyond just looking at the location of the shots, and not every shot attempt is a scoring chance, according to this model. Lastly I look at high danger scoring chances compares to medium danger scoring chances and goals.
I hope you find this useful and interesting. As usual you can connect with me on Twitter or send me any feedback, suggestions or comments through there as well.
the interactive dashboard can be found here: https://public.tableau.com/profile/rj7974#!/vizhome/PP9ScoringChances_newversion2018/PuckPossessed9p1
Cheers,
RJ