by Josh Fyman
A cliché that players, especially those on wild-card teams like to dredge up this time of year is that records are no longer relevant, that everybody is now 0-0. The whole idea sounds like bland motivational speak. After all, wouldn’t it stand to reason that teams with superior records would be more likely victors in playoff games? Well, I’m here to tell you that this is only slightly true. In fact, the cliché that all records are dialed back to zero has more credence when one looks at the numbers.
The first, most rudimentary analysis would be to correlate a team’s winning percentage in the playoffs with their records during the regular season. Since the abbreviated playoffs provide a small sample size, I went back five years and correlated the regular season winning percentages of all playoff teams with their winning percentages in the playoffs. The results are illuminating. There is only a 0.14 correlation between regular-season record and playoff record, which is barely significant. Granted that the data are skewed somewhat by the fact that teams that earn a bye do not get to accumulate as many wins, and therefore, suffer a worse playoff winning percentage in the event that they lose. This problem is erased, however, by comparing wild-card teams to each other and bye teams with each other. When examining only bye teams, the correlation between regular season and postseason winning percentage actually drops to 0.10, which is not significant.
Another school of thought is that the teams that finish the hottest are best suited for playoff success. To test this theory, I correlated playoff teams’ December records over the past five years with their playoff success. Turns out that there is only a 0.18 correlation between teams’ performances at the end of the season and their performances in the postseason. Bye teams’ performances are a little more predictive of their playoff performances, with a correlation of 0.23, but that still is not too much.
To drive home the point, over the past five years, in playoff games in which two teams with different records played each other, do you know the likelihood of the team with the better record winning? Ready? A whopping 51.8% probability. So, if you’re picking playoff games based on which team has the better record, you’re just about as well of flipping a coin.
Not only do teams with better records fare only slightly better in playoff games, but it doesn’t even much matter how much better one team’s record is than the other. In a correlational analysis, there was no significant relationship between how many games separated the two opposing teams’ records and the probability of an upset (upset being defined here as the worse record beating the better record). In short, a game with records separated by one game was no more likely to result in an upset than a game with records separated by three, or even four, games.
Is there no way to predict playoff games with some accuracy? Of course there are models that will provide results better than 50/50. Looking at records, however, offers no help whatsoever.
Tuesday, December 30, 2008
by Josh Fyman