This is to serve as a glossary for the stats & I keep track of on this blog, what they mean and what significance they have.
To track zone entries, I chart the time of the entry, if the attacking team carried the puck into the zone or dumped it in, the area of the ice where the entry occurred and which defending player was guarding the blue line at the time of the entry (if there was one). I also count if the player entering the zone had support from a teammate and who that teammate was. If the puck was dumped in, I also track whether or not the puck was recovered by the attacking team and who the player was. What we’re left with is a spreadsheet that looks something like this:
Bloggers started tracking zone entries during the 2011 playoffs and a few continued to do so during the 2011-12 playoffs. Through a study done by Eric Tulsky at the Sloan Sports Analytics Conference, it was determined that entries done with control of the puck lead to twice as many shots as opposed to ones without control. Thus, carrying the puck in has been determined to be the optimal method of entering the offensive zone. Since then, there have been other cool studies done based on this like how repeatable neutral zone play is compared to offensive & defensive zone play, the different types of neutral zone players, how effective playmaking combined with strong neutral zone play and a lot more.
I feel like we’re just scratching the surface with what we can do with this type of analysis and it’s usually the starting point of all of my breakdowns.
Starting with the playoffs, I started tracking my own shot attempts for games. Part of it was so I could add passes without NHL play-by-play data screwing it up (more on that later), and I also wanted to add more context to the shot because everyone knows not all are created equal. In addition to who took the shot, I also track which area the ice the shot was taken, whether or not there was a screen, if the shot was deflected, if the goalie had to move laterally to make the save and if the shot came off a rebound. Which player made the screen/deflection/rebound chance is also tracked. In the end, we’re left with data that looks like this.
We can also break things down like this to see the different zones where a shot was taken. I’m still trying to figure out the best way to display this on an individual level, though.
If there’s anything else you feel I should add then please let me know.
Also added to the shot data is whether or not there was a pass. This is largely influenced (i.e.stolen) from Ryan Stimson’s passing project, which is one of the best and most interesting data collection projects going around right now. The method behind tracking the data is pretty straightforward, in that I track the last three players who made a pass before a shot and which zones they occurred in. Ryan’s studies on this over the last couple of years have also shown that passing is a repeatable skill and generating shots through passing plays is more correlative to goal scoring than individual Corsi. Which intuitively makes sense. You’d expect shots that come off passing plays would be more difficult for a goalie to stop than vice versa.
The results from the playoffs have already been interesting and we can look at things like how much each player did to contribute to the offense when he was on the ice.
We can also take a more detailed look at what each player did to contribute to offense by breaking down shots & passes:
and this is just scratching the surface of what we can do with it.
I started tracking zone exits for my old blog, Shutdown Line, and continued to do so for my All Three Zones Project. For this, I tracked how many times each player touched the puck in the defensive zone, whether they got the puck out and whether they did it by carrying the puck out, passing it to a teammate or dumping the puck out. I also tracked if they turned the puck over or iced it. Unfortunately, this is something I haven’t found the time to test so it’s all just explanatory data right now (think of it as a freebie or something we might be able to use later).
Also, I’m tracking zone exits differently here than I did for the project. The biggest change is that I no longer track every time each player touched the puck in the defensive zone, as I felt that created a lot of noise and useless data. Instead, I’m tracking zone exit attempts and the results. In other words, how many time each player attempted to exit the zone and how they did it (by carry, pass, dump-out or clearing it out of the zone). I’m also charting failed exits (which turnovers are lumped into) and if the exit led to a zone entry. These are classified as “Transition Plays” in my tracking sheet. I’m also checking whether or not the player exiting the zone was pressured by a forechecker. This is determined by if there is an opposing forechecker at least a stick-length away from the player attempting to exit the zone. I added this wrinkle to see if certain players who are better at beating a forecheck when exiting the zone.
The end result looks something like this:
Again, this is all just explanatory data now, but maybe there’s something we can use from it once we get more data? Guess we’ll only know if we find out.
If there’s anything else you want me to add or start tracking before the year starts, let me know!
Sites I Use
Obviously, I don’t track every single stat known to man, so here’s a few sites that I use for on-ice shot info, time on ice data, regular shot stats (Corsi, Fenwick, Score Adjusted Fenwick, etc.) and shooting/save percentage stats:
Natural Stat Trick: Great site for game-by-game stats.
Hockeystats.ca: Another great source for real-time game data.
Hockey Analysis/Puckalytics: Great site for full-season data and info on linemates.
Hockeyviz: Fantastic resource for hockey graphs and making hundreds of games worth of data very easy to sort through and visualize.
Hockey-Graphs: Superb blog which inspires a lot of my posts. Also home of Ryan’s Passing Project, which I went over earlier.
Behind The Net: The original hockey stats resource which I still use today.