Which Game Should You Win?

The other day I was thinking, “What game in a 7 game playoff series is most closely correlated to winning the series?” Fans obviously cheer hard for their team every game in the playoffs, but if they knew that winning a particular game gave their team the best chance to win the series, perhaps they’d pull out all the stops. So, with this interesting question in hand, I went to see what the data said.

Hockey Reference is a treasure trove of hockey statistics and historical data. In order to get some answers to my questions, I pulled all of the playoffs series going back to 1943 (the first year where each round was decided by a 7 game series). This got me a total data-set of 598 series, and a total of 3363 games (so much hockey!).

Now it was time to crunch the numbers. Since I now had this really cool data-set, I decided to calculate some interesting tidbits before answering my original question. The first of these tidbits was to see what percentage of the series ended in 4, 5, 6 or 7 games:

Another interesting tidbit is the idea of home ice advantage. Teams play 82 grueling hockey games throughout the regular season and once you’ve met the “make the playoffs” bar, the only other advantage to doing well in the regular season is the idea of home ice advantage. You would therefore hope that it actually is an advantage to your hockey, not just an advantage to your team’s owner for getting to host an extra game in his arena. Since 1943, the home team (defined as the team that hosted game 1) has won 64.5% of all playoff series. In addition to that, out of the 108 four-game series sweeps there have been, the home team won 81 (75%) of them. So I think it’s fair to say that home ice is an advantage.

Alright, enough beating around the proverbial bush - time to answer the question that took me down this rabbit hole. As I said, I wanted to know which game in a 7-game series has the highest correlation with winning the series. The obvious answer is game 7, considering 100% of the teams that won game 7 won the series. This isn't very interesting, though, so let’s dive in. The following chart shows the percentage of teams that won the given game who also won the series:

Well, this is awkward. That chart isn’t very interesting at all. Essentially the first 4 games are a toss-up (with Game 2 having a slight edge), and then we see the percentages go up for the elimination games as you would expect. Clearly if your team has a chance to end the series in a game, you should cheer as hard as possible for that to happen. I did a little more analysis however and found something interesting. Later in the series, the team that won Game 5 in a series that went past Game 5 won the series 60.6% of the time. But for Game 6, the team that won game 6 in a series that went to Game 7 only won the series only 47.9% of the time. So much for all that “momentum” talk.

In the end it is the humble opinion of this writer that winning any game in the playoffs is probably your best bet. However, if you’re looking for the most statistically advantageous games to win, it appears that Game 2 and Game 5 are the ones to win. 

More analysis to come so stay tuned...