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A season's worth of Philadelphia Flyers zone entries: The opening statement

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All year long, Geoff has diligently tracked zone entries for us. In every game, every time someone brought the puck into the offensive zone, he wrote down who had the puck and how they sent it in -- whether they carried it in, dumped it in, etc.

There is a ton of information in that data. In the coming days we will be digging through it in detail, but we will start here with an overview. Think of this like an attorney giving an opening statement; we'll cover everything briefly, giving you an idea of what you are going to see, and then the rest of this series will present the detailed evidence to support the claims we make here.

What we did

Geoff watched the games -- I know, it's crazy, but it's true. He recorded every zone entry where the team was trying to generate offense (i.e. not counting plays where they dumped the puck in and changed lines without really trying to recover the puck). He recorded which player sent the puck in, so we could assess individual on-puck contributions. He also noted the time on the clock, and a one-letter code for what type of entry it was. Counting how many times each team advanced the puck into their offensive end and how they did it gave us a measure of who was winning the neutral zone.

We then used the NHL play by play for the game to get a list of stoppages and divided the game up into segments that ran from one zone entry (or faceoff) to the next. The play by play also told us how many shots and goals were taken during each segment, which gave us a measure of how successfully the team generated offense from each offensive zone possession.

Finally, we used the NHL shift charts (or more precisely, we used Vic Ferrari's scoring chance script which uses the NHL shift charts) to figure out which players were on the ice for each zone entry, so that we could assess how the team performed with a given player on the ice.

Overall observations

This effort made it clear that maintaining possession of the puck as you enter the offensive zone is crucial to offensive success. When a team carried the puck across the line or passed it to a teammate, they generated more than twice as many shots and goals as if they played dump-and-chase, which helps explain why the Soviets preferred regrouping to dumping the puck in. Winning the neutral zone meant not just advancing the puck, but advancing it with possession.

It also became clear that score effects were a significant factor. It has long been known that teams adapt their strategy depending on the score and that it has an impact on shot differential. This work showed that the score effects arise primarily from teams conceding the neutral zone when they have a lead -- they still generated about the same number of shots per offensive zone possession, but they generated far fewer offensive zone possessions.

To manage score effects, we focused primarily on zone entry results when the score was close. There, we found that the Flyers outplayed their opponent in the neutral zone, generating more offensive zone possessions and retaining possession on a larger fraction of those possessions. However, they gave about half of that advantage back in the attack zones, as they allowed their opponents to get more shots per offensive zone possession than they generated at the other end.

Individual efforts

Recording which player sent the puck into the offensive zone allows us to measure players' individual puck-handling contributions to winning the neutral zone. A player's zone entry total gives us a measure of how involved he was in moving the puck forwards through the neutral zone. The fraction of those entries that were executed with possession of the puck gives us a measure of how successful he was, how impactful his contributions were.

Thus, we have some players -- Jaromir Jagr, Claude Giroux, Jakub Voracek -- who were heavily involved in pushing the puck forwards and extremely successful at it. We have some -- Maxime Talbot, Brayden Schenn, Scott Hartnell, Zac Rinaldo -- who rarely touched the puck in the neutral zone and were not particularly good with it.

But there was one line that made no sense. Wayne Simmonds and Daniel Briere played together for most of the season. Briere was extremely good at keeping possession of the puck across the line, but didn't get many chances. Simmonds got the puck a lot, but just kept dumping it in. They had two of the worst shot differentials on the team despite getting a lot of starts in the offensive zone against weak competition, and one can't help but wonder if this zone entry inefficiency was part of the reason for that.

Off-puck contributions

The team's results with a given player on the ice can give us an indication about his off-puck contributions, including at the defensive end. For example, when Giroux, Jagr, and Scott Hartnell were on the ice, the Flyers had their best neutral zone performance and were above average in the offensive zone, but the team was at its worst in the defensive zone with that line on the ice. They may have taken on strong competition and beaten them, but that was more the product of offensive skill than two-way play.

Andreas Lilja is another interesting example. The team was much less likely to win the neutral zone with him on the ice than with him off it; they got fewer zone entries with him on the ice than with any other defenseman. However, he was by far the most effective at preventing the opponents from entering the zone with possession, and so while the team's overall neutral zone performance with him on the ice was not good, he made the opponent dump the puck in often enough to keep it from being a disaster.


There is an awful lot of information in our zone entry data, and over the next few weeks we will flesh out the details hinted at here. We will look at how the Flyers did against each of their conference rivals, at each individual's results, and at what those results can tell us about a player's talents.