16 May 2009

Home Ice Advantage - Examination

It's generally known and acknowledged that over the long term, all things being equal-ish, the home team will win slightly more games than they lose.  Off the top of my head, I would imagine the home-ice winning percentage would probably be somewhere between 55-60% in the playoffs.  I was going to compile this data for another post I was going to do anyways, where I was mostly only interested in straight league-wide winning percentages anyways, but as I began compiling the data, I began to wonder about what trends might be seen in the data, on a per round basis, and more interesting, on a per-conference basis.  

My personal expectations were to see a higher than average home-ice winning percentage in the first round, for the obvious reason that in the first round, you usually see the biggest mismatches in terms of good teams versus bad teams.  Thus, the good team (who has home-ice advantage) should usually win, meaning they will more likely collect those wins on home ice.  n subsequent rounds, I expected to see this drop to a level more in line with the average, or maybe even slightly below average, if the average was pulled up too far by the large number of first round games, in which home-ice advantage would be more apparent.  

As for a per-conference viewpoint, I wasn't entirely sure how this would work.  I have only been watching hockey for the last 14 years, which also has coincided with a general rise in power in the Western Conference versus the Eastern, as well as a definite distinction in styles.  However, this spreadsheet goes back 22 years.  I expected to see the Eastern Conference have a slightly higher home-ice advantage, at least in the earlier rounds, based on my own anecdotal observations that the West plays a considerably more tight-checking and defensively-oriented game than the East over the time period of my being a hockey fan.  I'm guessing that the conservative style of the West is more condusive to the occasional upset, than attempting to offensively out-gun your opponent.  Over time, I figured this should lead to seeing more upsets in the West, lowering the home-ice winning percentage for the West.  The success (at least in the West) of such teams as the 2003 Ducks and 2006 Oilers would seem to support my theory, at least on the surface.  

All data is through the 2009 Conference Semifinals.
HIW% = Home-ice Winning Percent

Total Playoffs
NHL HIW% = 56.0% (1043 wins / 1864 games)
Western Conference HIW% = 57.3% (533 wins / 931 games)
Eastern Conference HIW% = 54.7% (510 wins / 933 games)

NHL HIW% = 57.6% (586 wins / 1017 games)
Western Conference HIW% = 57.5% (295 wins / 513 games)
Eastern Conference HIW% = 57.7% (291 wins / 504 games)

NHL HIW% = 55.5% (272 wins / 490 games)
Western Conference HIW% = 57.0% (138 wins / 242 games)
Eastern Conference HIW% = 54.0% (134 wins / 248 games)

Conference Finals
NHL HIW% = 51.5% (124 wins / 241 games)
Western Conference HIW% = 55.9% (66 wins / 118 games)
Eastern Conference HIW% = 47.2% (58 wins / 123 games)

Stanley Cup Finals
NHL HIW% = 52.6% (61 wins / 116 games)
Western Conference HIW% = 58.6% (34 wins / 58 games)
Eastern Conference HIW% = 46.6% (27 wins / 58 games)

I expected to see HIW% decrease as the playoffs continued, because you would see less one-sided matchups as the playoffs went on.  In the West, this effect was slight, dropping only only from 57.5% to 55.9%.  The slide in the East was much more dramatic though, from 57.7% down to 47.2%.  I really have no explanation for this.  Figuring this out might be a little tricky.  

The SCF winning percentages seem to reflect two things in these results.  First of all, the West has been the better franchise in most head-to-head matchups for a significant amount of time in this study.  Of the 22.5 playoff seasons we're looking at here, the West has won 12 cups, or 12/22 (54.54%).  The West has not won a lot more Cups than the East, but in those Cup wins the West has completed 4 sweeps of the SCF, versus only 2 for the East.  Secondly, whatever the reason is for the Western HIW% being higher than the Eastern HIW%, this may hold true in the SCF, giving the West a significantly higher HIW%.  

I'm working on some conclusions to draw from this data, and should have those conclusions up soon.  Feel free to offer what thoughts you have on this data in the comments.  I think the Eastern Conference data is particularly interesting.  

1 comment:

  1. Hey Joe, I think you're underestimating the Western Conference "style" when you take these figures into account. Altho the sheer # of goals scored is almost always higher in the East, I wouldn't call the Western style "conservative" outside of a few teams, like the Canucks, Wild and Blue Jackets, which play the six-goalie system.

    More to the point, I think (and maybe I'm generalizing), but for better or worse the class of the West has been the Wings, Avs, Stars, Ducks and Sharks, teams which could hardly be called "conservative" but can absolutely be called "defensively responsible".
    (Well, maybe not the Avs)
    In any team sport, when one team has tremendous success their opponents start to copy their style. I think the Lidstrom-era Wings have pretty much set the standard in the West for having smart, non-thuggish d-men and running the team through them, rather than through a flashy first-line center. As a Wings-hater (Stars and Blackhawks fan), it pains me to say that but it's likely true.
    So when the West comes up huge statistically, it makes sense because Good Teams Take Care of Their House: whether they're winning 2-1, 1-0 or 5-1. I think goal differential might tell another story altogether, but that's another blogpost.
    Keep up the good work, Joe!