Basketball Prospectus: Unfiltered Everything Else is Fluff.

April 20, 2009

Good News for the Celtics and Spurs

Filed under: Uncategorized — Kevin Pelton @ 6:22 pm

Piggy-backing on Bradford’s post just below. . . .

Having lost Game 1 Saturday on their home court, Boston and San Antonio are desperately in need of a Game 2 victory tonight to avoid facing a deep 2-0 hole heading out on the road. Portland will be in the same position tomorrow, as will Orlando on Wednesday. History tells us the road teams will have a hard time completing the sweep of the first two games.

The eagle-eyed readers at Blazer’s Edge noted that the site has comprehensive data on seven-game series in the NBA as well as other sports. They break down team performance by Game 1 outcome. From 2003, when the NBA went to best of seven in the first round, through last year, 12 lower-seeded teams went on the road to take Game 1. In Game 2, those same teams were 2-10. (Oddly enough, one of those two teams was the 2005 Houston Rockets, who ultimately lost the series in seven games. The other was last year’s Utah Jazz, who went up 2-0 on the Rockets and beat them in six games.)

That site’s breakdown was fascinating to me because I wanted to take a look at one of my subjective beliefs–that the Game 1 loser actually takes something of an advantage into Game 2. Alas, the first-round data doesn’t prove that out. Home teams are slightly better in Game 2 coming off a win (.861 winning percentage) than having lost (.833). However, that’s probably got something to do with the large talent differences in the 1-8 and 2-7 matchups. When you look at all seven-game series, home teams win Game 2 68.3 percent of the time after winning Game 1 and a much stronger 74.2 percent of the time after losing.

Why do we see this effect? Part of it, surely, is nothing more than old-fashioned regression to the mean. But I also think it’s easier for teams to make adjustments after a loss than it is to do so after a win. Winning can hide some flaws. In some ways, this theoretical effect is similar to the one researchers at Penn found this year where teams that trail by small margins at halftime tend to come back to win more than 50 percent of the time. While there are still questions about the robustness of that study, the underlying theory makes some sense.

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