Introduction to the Transition Project

This is one of my favorite plays:

Almost every team is coached to make their opponent fight for every inch. Skjei’s end-to-end rush cuts through those defenses and leaves his team in a much better position than when he started.

But just how much better off did he leave them? How does that compare to alternative outcomes? And which players are the best at making these plays? We have unanswered questions about transitional play. We’d like to study them in more detail, but the gif above doesn’t appear anywhere in the league’s play-by-play data to help conduct analysis.

A Brief History of Transitional Play Studies

In order to understand these plays, analysts have turned to manual tracking. They recorded zone exits, zone entries, and passes, which changed what we knew about hockey. One of the first forays into measuring neutral zone contributions was done by Tulsky et al.. Garik16 has expanded on that work, Jessica Schmidt showed new findings from zone exit data, Ryan Stimson incorporated passing data, CJ Turtoro looked at repeatability and productivity, and many others have contributed to our understanding of how NHL teams play.

Transitional play tracking continued to grow thanks to Corey Sznajder, a one-man force of nature in neutral zone tracking. He tracked every zone entry in the 2013-2014 season and is now tracking exits, entries, and passes for the past three seasons.

His work has provided public analysts with a treasure trove of data, and I’d encourage all of you to help support it. But that trove remains understudied. That’s why I’m launching The Transition Project.

The Transition Project

The Transition Project is an effort to study how hockey players get the puck from one end of the rink to the other. Over the next few months, I’ll be sharing insights from Sznajder’s dataset. I hope this project will help all of us better understand transitional play, including breakouts and forechecks. Specifically, zone exits and passing data have gotten little attention. I’m particularly excited to combine this data with traditional play-by-play information so we can see, for the first time, what happens to the entry after each exit, and vice versa.

For an early preview, check out my RITHAC presentation. There, I discussed the impact of forecheck pressure, the value of maintaining possession on zone exits, and visualizations of defensive zone passing networks.

I don’t want to be alone in this effort. Whether you’re a seasoned data scientist or a hockey fan looking to try data analysis for the first time, transition data is a great area to study. I can’t make the full datasets 100% public because they belong to Sznajder, but I’m happy to share what I can. So, if you’ve supported Sznajder in exchange for access to his data, you can have access to my data as well. Message me at or on Twitter and I’ll share my files, which combine all his raw data across teams and clean it up for easier calculations.

I hope you’ll follow along, or even contribute yourself. For sticking around so far, here’s a video of Ilya Kovalchuk with another one of those glorious transition plays:

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