The general point you are making is well taken. Better teams should also be more likely to have better records over the last 10 games. Thus, if you were simply to look at correlation coefficients between records in the last 10 games and probabilities of winning series, what you would be capturing, to a large degree, is that better teams win playoff series more often.

This is why multivariate regression techniques are so important. By running a regression, we were able to "control" for the underlying qualities of the teams in the series. By having a term that captures their relative strengths, the momentum term really is separate from the underlying quality of the team.

In the regression, we considered the relative records of the teams as well as their relative "momentum". That is, there are teams that were 10 points better, for example, than their opponent who had better records over the last 10 games (which you would expect), but also teams that were 10 points better but had worse records. What we are finding is that, among teams who were 10 points better than their opponents, those that closed out the season (relatively) strong won more often than those who finished (relatively) weak.

I hope this helps, and thanks for your comment. Again, I'm sorry it took me so long to notice it!

]]>I'm skeptical to attribute this data to momentum as opposed to any other possible factor due to the previous 5 games not being representative of future results; in my mind, it would be that sample that would convince me of momentum, instead of last ten games. I understand your point of resting a teams best players, but I still find myself skeptical to accept the conclusion.

Regardless, I thought the article was very interesting and well put together. Good read ]]>