In the NBA playoff system, the Eastern Division champion plays the Western Division champion in a seven-game series. The first two games of the series are scheduled at the home arena of the team with the most wins during the season. Let’s call them Team A. The next three games are scheduled at Team B’s arena, and the final two games are scheduled at Team A’s arena. This can be described as a 2-3-2 schedule. [Prior to 1985, a 2-2-1-1-1 schedule was used.] The first team to achieve four wins is the NBA champion. Thus, the series may last for 4, 5, 6, or 7 games.
Team A, if the series lasts all seven games, will play four games at its home arena, while Team B will only have three home games. Since basketball teams tend to win more often at home than away, Team A is said to have “home court advantage” for the series. [Note that if the series lasts 4 games or 6 games, each team plays the same number of home and away games. If it lasts 5 games, Team B has three home games while Team A has two. This is easier to visualize if we denote the 2-3-2 schedule as AA-BBB-AA, where A and B represent at which team’s home arena the game is scheduled.]
Team A certainly seems to have been advantaged by the schedule. Not only do they play more games at home than Team B in a 7-game series, but since the first game is played in their home arena they have a better chance of jumping out to a 1-0 lead in the series. However, sometimes, Team B wins the first game. When this happens, Team B is often said to have “stolen the home court advantage” from Team A. Certainly “stealing the home court advantage” is a catchy phrase, but is there any foundation to this assertion, either in logic or in actual results?
First, let’s look at the logic associated with Team B winning the first game. In a 4-game series, Team B now has two of the remaining three games at home (A-BB); if the series lasts 5 games, three of the four remaining games at home (A-BBB); and if the series lasts 6 games, three of the remaining five games at home (A-BBB-A). In a 7-game series, they now have three home games and three away games, the same as Team A (A-BBB-AA). So, from a logical standpoint, Team B has gone from having home court advantage only in a 5-game series to having home advantage if the series last for 4 games, 5 games , and 6 games. They’ve also moved from an “away disadvantage” in a 7-game series to the same number of home and away games. Logically, they certainly appear to have improved their lot.
But, does actual performance data support the logic? In the fifty NBA playoffs from 1960 through 2009, Team A won the series 34 times, for a 68 percent winning advantage. Team B, naturally, won 16 series for a winning percentage of 32. Certainly home court advantage seems to have served Team A well. However, in those fifty series, Team B won the first game of the series 13 times. Did they steal home court advantage by winning the first game? Well, they won seven of those thirteen series, for a 54 percent winning record. Remember, Team B only won 32 percent of the series overall. This is quite an improvement!
So, can an NBA team steal home court advantage? Both logic and historical data seem to indicate they can, or at least erase the disadvantage they had at the beginning of the series.