May the odds be in your favor

Or the story about the Finnish hockey league play-off odds. (And how one of these days I’ll actually have to read and/or watch The Hunger Games, considering how much I quote them.)

The play-offs are in full swing in Finland, at least if by “full swing” one means the extra “pity play-off” round went as it was supposed to go given the regular season standings, and the next round starts today.

I’ve posted earlier about the play-off probabilities in general, but this time I decided to focus on something slightly different. I though I’d calculate the odds of each match-up, simplifying heavily by considering the regular season win percentages as a proxy for team quality, but by considering home and away win percentages separately. There are two reasons for this:

1) Home advantage is an actual thing. It has been shown to exist in studies, and can be tracked down to small, yet significant, rules favoring the home team. Plus the “intangibles”, such as fan encouragement, and/or the pressure to play well because your mom is watching.

2) The teams in the Finnish league have very different win percentages when broken down to home and away games.

Taking a closer look at this, the win percentage is simply games won over games played. Contrary to the Finnish league’s (and all other leagues’ for that matter, and this is a whole other issue in and of itself) I treated each win as equal, regardless of whether it took place in regular game time or in overtime or shoot-out. A win is a win.

This revealed some rather disturbing issues. For example for Blues, a team that finished fifth in regular season and now faces JYP in the play-offs. Blues won 36 games in regular season. JYP, the team that will have home advantage in the play-off series, won 33 games. In fact, the only team that won more games than Blues, was Kärpät, the team that won the regular season! So now we have a team with win percentage of 60% playing a team with 55% win percentage, and the weaker team starts at home.

win percentages home and away

Once the win percentages are calculated separately for home and away games, the figures prompt some interesting questions. Like stated above, the home advantage is a real thing, largely because of the several points in the rules advantageous to the home team, for example the right to put players on the ice last, and thus making it easier to play specific players against other teams top players. And true to form, the teams making the play-offs had higher win percentages at home than away, except for SaiPa (8th in regular season) who played the same regardless of the arena.

Since the rules are the same for all home teams, one could argue that the differences in home win versus away wins changes according to the non-rules related variables, such as home crowd input (the players often mention an active home crowd is “the extra player on ice” giving them an advantage, and even yours truly isn’t quite cynical enough to think that is simply lip-service to sell tickets) or unintentional bias by the referees in favor of the home team, often credited to a pressure from active crowd.

While the above would feel intuitively pleasing, and is supported by the large differences in the win percentages of famously active and attentive home audience at Kärpät and HIFK games (for Kärpät, the home w% is 76,67 and away w% 56,67, whereas for HIFK they are 66,67% and 43,33% respectively), the theory fails for Blues. Displaying some of the weakest attendance figures in the league, Blues is really rocking it on home ice: their win percentage at home is 76,67%, better than all other teams’ except for Kärpät with whom they tie. When away, however, they tie for the second-to-last place with JYP and HIFK with 43,33%.

Another team that needs to up their away game is KalPa. Second-highest home win percentage (behind only of Kärpät and Blues) of 70% is brought down to a mere 55% overall, when you only win 40% of your away games. That’s the weakest of the Top 8 -teams.

What this means in terms of the play-off match-ups, then?

First I used only the over-all win percentage as a measure of team strength, that is, ignored the home team advantage, and calculated the odds of each team winning their respective best-out-of-seven series. Kärpät-SaiPa series would go to Kärpät with a probability of 51,42%. Tappara would defend their higher-ranking regular season finish, winning the series against HIFK with 50,71% probability. Lukko-KalPa would end up with a surprise victory by KalPa, at least with the likelihood of 51%. And with a probability of 51,46% visiting team Blues would continue to win more games than JYP.

But, since the home ice did seem to influence rather largely to the teams’ win percentage (unless you’re SaiPa), what are the odds of the home-starting teams taking the series? Unlike in the NHL where the team finishing higher in regular season hosts the first two games and then visits for two after which they alternate if needed, in Finland the home team changes after every game. Still, in a full 7-game series that gives 4 home games to the team with higher rank, as opposed to three.

In the first two pairings, regular season winner Kärpät playing SaiPa and second-placer Tappara playing HIFK, the home team (the team starting home) simply increases their odds of winning. Kärpät takes the series with a probability of 62,51% and Tappara with 56,57%. The difference in team strengths is considerable enough, that even if we turn things around and pretend the weaker team gets to start at home (SaiPa and HIFK, respectively), Kärpät would still win with probability of 60,24% and Tappara with 51,86%.

With the Lukko-KalPa match-up the odds are in Lukko’s favor as long as they get to start at home (which they do). The home advantage means they have a 51,44% chance of making it to the next round, whereas if the teams started on the KalPa home ice, KalPa would take the series with the probability of 54,5%. Remember that with the aggregate win percentages the series would also go to KalPa (51%). That’s because KalPa has a higher win percentage than Lukko, 55% to Lukko’s 51,67%, due to actually winning more games in the regular season.

With home advantage, JYP with over-all win percentage of 55% clinches the series with probability of 50,28%. If they started at Espoo, Blues’ solid performance at home would bring them the series with a probability of 57,64%. As stated above, with aggregate win percentages Blues (with 60% win percentage) would win the series with a probability of 51,46%. So really, the odds are in Lukko and JYP’s favor simply because of the home advantage they got due to the way wins in regular time versus overtime are valued in the league.

What’s going to happen, then?

Well I can say for certain that the following will happen: either the team starting at home or the team starting away will win. It’s the play-offs. Best out of seven games. Anything can happen. The odds above are not a prediction, they are simply what it says on the tin: probabilities of winning the best-out-of-seven series, given regular season win percentages. It doesn’t take into account team-versus-team performance, or game plans, or who’s injured, or who’s having a bad day, or which team’s got their groove on. All of which will play a role in a play-off series.

But the above does tell us something: if we assume the point in hockey is to win games, and thus the team that wins more games is better than the team that wins less games, we are not rewarding the best teams of the regular season with home advantage in the play-offs.

We’re actually leveling the playing field.

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One thought on “May the odds be in your favor

  1. Hei,
    Mulla on ollut yksi idea SportsEcon paperille, mutta muiden kiireiden vuoksi en ole ehtinyt koko ideaa toteuttaa ja en varmasti lahitulevaisuudessa sita yksin ehdi tehdakkaan. Tormasin juuri tahan sun blogiin ja ajattelin kysya jos sulla ois mielenkiintoa co-authorata paperia. Jos kiinnostaa laheta emailia niin kerron tarkemmin mista on kyse.
    Salomo

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