NHL Game 7’s are awesome, and in the next two days, we get two such contests – Dallas vs. St. Louis and San Jose vs. Nashville.
Here’s a primer on what to expect with respect to team behavior in these games. All of my findings used data from the nhlscrapr package in R for the 10 years of postseason action between 2006 and 2015.
Fewer penalties, slightly fewer goals in Game 7’s.
Nate has a nice chart covering the tendency for teams to accumulate fewer penalties in game 7’s, relative to other games in the series. I found roughly the same thing; about 11 total non-matching penalties per game during the first six contests of a series, compared to just seven in game 7’s. That’s about eight more minutes of even strength to expect in a Game 7.
Perhaps the fewer power plays awarded in game 7’s are driving a small but noticeable difference on the total number of goals; while games 1-6 average 5.3 goals per game, game 7’s average 4.9.
Penalties are less likely to be called at the beginning of Game 7’s.
Here’s a chart of the per-minute penalty rate comparing game 7’s to game’s 1-6. Each line reflects a smoothed curve, and the grey area reflects our uncertainty in each curve’s trend. Rates are adjusted to reflect the number of penalties we would expect if the rate of whistles for that minute of play were extended for an entire game.
The biggest difference in penalty rates between game 7’s and other games in a series looks to be the first period, where penalties are consistently called less often. This could be a combination of factors – players adopting a safer style of play, for example, or a referee’s hesitancy to call possible violations. Interestingly, these results mirror those from the NFL, where many judgement calls are rarely whistled to start a game.
There are also smaller differences in periods 2 and 3, and marked differences in the game’s final minute. However, note that rate differences at the end of the game are perhaps not too surprising given the frequent scrums in earlier games where teams do silly things like trying to “send a message.” Sidenote: I wonder how style of play would change if penalties at the end of a game carried over to a team’s next contest.
Here’s a similar plot looking at goals (empty net goals were excluded).
Note that the standard error bars for each curve were fairly large and overlapped throughout a game, and so differences between the two curves should be taken with a grain of salt. There is slightly less scoring throughout most of game 7’s, particularly at the end of the first period and at the beginning of the third period. Teams operate at about a two goals-per-game pace to begin the third period of game 7’s, for example.
More pressure, more call reversals?
In work a few years back (ignore the Excel chart! I was learning R at the time), Kevin and I found slightly higher rates of make-up calls in Game 7’s, relative to other games in a series. This came on top of the higher frequency of make-up calls in the postseason, relative to regular season action. Here, I’m defining a make-up call as one that works to even out the total number of penalties each team has.
A few years later, that trend still seems to hold. When a home team has exactly one more penalty that its opponent, it has received the next power play 58% of the time during the regular season. That number jumps to 62% in postseason game’s 1-6 and 68% in game 7’s. When owed two or more penalties, the home team has been awarded the next power play 61% of the time in the regular season, 65% of the time in game’s 1-6, and a remarkable 78% of the time (18 of 23 sequences) during game 7’s. So, if the home team gets behind on penalty differential, expect that to even up by game’s end.
Differences in postseason call reversals are not as evident when looking at if away teams are owed power plays. Across each game number, away teams that are owed penalties are given the next power play about 57% of the time.
StatsbyLopez 