In the 1983-1984 season, the NBA switched to a playoff system much like the one currently in place. A total of 16 teams make it to the tournament, and every team plays every round. So, every season has 15 series total. From 1984 to 2003, the first round was a best-of-five series. Since then, all playoff series are best-of-seven contests.
While the number of teams and number of series have remained constant, the seeding has gone through several permutations, giving different seeding advantages to division winners. However, the home-court advantage always goes to the team with the best record.
For example, this year the Boston Celtics finished first in the Atlantic Division with a 39-27 record and the Atlanta Hawks finished second in the Southeast Division with a slightly better record, 40-26. As the division champion, the Celtics were guaranteed a top-four seed, despite having finished with the fifth best record in the East. This meant that as the four seed, home-court advantage was given to the five seed. (Note: this had no effect - however, had the Celtics won the division with the eighth best record, they would have still faced the Hawks instead of the #1 seed - the Bulls). In my analysis, I used the NBA's home-court advantage to determine the "higher seed."
Every game has its own flavor. From Game 1, with the anticipation of match-ups and rivalry to tense game 7s with seasons on the line. I went through the last 27 years of playoff series and found the winning percentages of the home team and the higher seeded team.
Now, on to the games!
Game 1
Game 1 is always a home game for the higher seed. The home team has won 76.05% of these games. This nearly matches the overall home winning percentage of the higher seed (75.95%).
If the underdog had won the first game, the second game is won by the favorite 79.38% of the time. If the favorite won the first game, the favorite goes up 2-0 73.7% of the time.
This means that favorite more often wins game 2 if they first lost game 1. The combination of the complacency of the underdog, already having snatched home-court advantage back and the desperation of the favorite at the prospect of getting into a two game hole before going into enemy territory leads to a significant increase in home winning percentage.
Overall after game 2 56% of series have seen the favorite up 2-0, 39% tied 1-1, and 5% have the underdog cleaning up in the favorite's house, up two games to none over the favorite.
Game 2
Like Game 1, Game 2 is always a home game for the higher seed. Two possible game 2's exist - the 0-1 game (with the lower seed having won the first game) and the 1-0 game (with the favorite winning the first game).If the underdog had won the first game, the second game is won by the favorite 79.38% of the time. If the favorite won the first game, the favorite goes up 2-0 73.7% of the time.
This means that favorite more often wins game 2 if they first lost game 1. The combination of the complacency of the underdog, already having snatched home-court advantage back and the desperation of the favorite at the prospect of getting into a two game hole before going into enemy territory leads to a significant increase in home winning percentage.
Overall after game 2 56% of series have seen the favorite up 2-0, 39% tied 1-1, and 5% have the underdog cleaning up in the favorite's house, up two games to none over the favorite.
Game 3
For game 3, the home team is always the underdog. In 20 of 405 attempts, the underdog is already up two games to none (5%). In 12 of these 20 games, the underdog takes a 3 game lead on the favorites (winning 60%). This isn't far from the overall winning percentage of the home team - they win 56.3% of game 3's overall. However, with such a small sample size, this isn't very useful information.
When the underdog is down 2-0, they win 58.15% of the time in game 3. If the series is tied, the home team wins 53.16% of the games. One might think that the home team would win more often after having won once on the road, but the opposite is true. The condition of the series (the higher seed not wanting to fall behind in the series) is more indicative of the result of game three than the idea that the teams might be more closely matched.
This could be a general trend, but is more likely an overlap of two different scenarios. The first scenario being that the higher seed is significantly superior to the lower seed, and facing a deficit in the series, really turns it on and dominates game 3. The second scenario being that they are actually closely matched and the home team wins most of the games.
In 5-game series, the favorites swept in 50% of their chances - 43 of 86 attempts. This number is the lowest winning percentage for the home team with at least 50 games played. This is probably a testament to the extremely high numbers of teams that were allowed in the playoffs when the league first switched to a 16-team playoff. In 1984, there were only 23 teams in the league, so 70% of the league made the tournament.
After game 3, of which 405 have been played:
When the underdog is down 2-0, they win 58.15% of the time in game 3. If the series is tied, the home team wins 53.16% of the games. One might think that the home team would win more often after having won once on the road, but the opposite is true. The condition of the series (the higher seed not wanting to fall behind in the series) is more indicative of the result of game three than the idea that the teams might be more closely matched.
This could be a general trend, but is more likely an overlap of two different scenarios. The first scenario being that the higher seed is significantly superior to the lower seed, and facing a deficit in the series, really turns it on and dominates game 3. The second scenario being that they are actually closely matched and the home team wins most of the games.
In 5-game series, the favorites swept in 50% of their chances - 43 of 86 attempts. This number is the lowest winning percentage for the home team with at least 50 games played. This is probably a testament to the extremely high numbers of teams that were allowed in the playoffs when the league first switched to a 16-team playoff. In 1984, there were only 23 teams in the league, so 70% of the league made the tournament.
After game 3, of which 405 have been played:
- 95 times (23.46%) the favorite winning 3-0 (43 times ending the series)
- 206 times (50.86%) the favorite is up 2-1
- 92 times (22.72%) the underdog is winning 1-2
- 12 times (2.96%) the underdog is up 0-3 (a 3-game sweep 5 times)
Game 4
For the 7 games played with the underdog threatening a sweep, only once has the favorite bounced back and took a game (Western Conference Finals, 2005 - the Suns stole game 4 but lost in 5 to the eventual NBA champs, the Spurs). The other 6 times, the underdog got the brooms out.
For the 83.47% of games that start with the series at a 2-1 tally (either the underdogs or the favorites with a one-game lead) the results are very similar, right around a 50% winning percentage. These are cases where neither team has its back against a wall. The previous performance in the series is indicative of the result of this game (although only to a small degree). If the lower seed is up two games to one, they go on to take a 1-3 lead 53.26% of the time. If the higher seed has the 2-1 lead, the lower seed only wins 50.97% of the time. A small, but interesting, difference.
The favorite has threatened to sweep (being up 3 games to none) in 52 of the 253 best-of-seven game series that have been played in the last 27 years. These series obviously represent the games where the favorite is significantly superior to the home team having won both of their home games and their only road game, and represents by far the highest winning percentage of any visiting team, winning 32 of the 52 tries (61.54%). In fact, the next highest away-team winning percentage in a seven game series is game 3 in a tied series, when the favorite wins to take a series lead 49.49% of the time.
Unfortunately, there is no way to compare the winning percentage of the best-of-five series sweeps to best-of-seven sweeps since the close-out game 3 is the first game played at the underdog’s home-court.
Game 5
While game 5 is usually a home game for the favorite, in the finals game 5 is the third home game in a row for the underdogs.
When the underdog has a 3 games to 1 lead going in to game 5, the higher seed wins 72.73% of the games to bring the series to a 2-3 tally. This is a high winning percentage, but still lower than the overall game 5 favorite winning percentage of 74.53%. This slightly lower winning percentage could be due to some game 5’s being away games for the favorite, or that the lower seed has to be a worthy opponent to have taken a three games to one series lead.
When the favorite is ready to clinch in game 5 with a 3-1 lead, they are almost always playing at home and have a remarkable success rate of 76.74%. This winning percentage is likely dominated by the higher seeds winning against an outmatched opponent that got a win at home in game 3 or 4.
With the series tied at two games apiece heading into game 5, the home team wins 74.32% of the games, to take a series lead. The majority of game 5’s that have been played over the last 27 seasons (55.43%) are of this type, with the series lead in the balance.
Game 6
Game 6 is usually played at the underdogs home-court (the exception being finals games, of which 6 underdogs have won on the road since 1984). Only two records are possible going in to game 6: 3-2 in favor of the top seed, or 2-3 in favor of the lower seed. Over the past 27 seasons, 66.43% of game 6’s have been 3-2 in favor of the top seed.When the top seed has a chance to win the series game 6, they are on the road, with two chances to clinch the series, while the underdog has their season on the line at home. In 46.24% of the games, the underdog pulls it out and takes the series to a game 7. Given the gravity of the situation, and that the underdog has already won two games, one might think that this would be more in favor of the lower seed, but in fact it is below the average winning percentage of the lower seed in their home-court (54%).
When the lower seed has won three games going into a game 6, they are relatively dominant - winning 72.34% of their chances to win the series on their home-court. This is easily the highest winning percentage of any other game by the underdog (except for the 6 times the lower seed has swept in the 7 times they had a chance to in game 4 at home).
This large gap in winning percentages in game 6 - in series that has already gone to 6 games - is surprising to me. Only one game of six separates the two teams and there is a 26% difference in winning percentage.
Game 7
In the 27 seasons that I analyzed since the playoffs switched to a 16-team format, 56 playoff series have gone to a game 7. The top seed has been dominant, winning 82.14% (46 of 56). Considering that the lower seed has already won 3 games against this team, its a very significant edge by the higher seed.
Playoff basketball is all about attitude and talent. The higher seeds usually have the talent, and when their backs are against the wall, the talent perseveres.
The difference in winning percentages depending on the record of the teams in the playoffs is astounding. Whether the difference is a testament to player’s will to win when the pressure is on, or if its an embarrassment that they don’t try hard enough in early games, I’ll leave up to you to decide.
I want to know what the percentage of a particular team winning a series after winning game 1, 2 and so on. Who is winning series or whether it is tied not being a factor. For example, Game 1 winner has won the series xx% of the time. Game 2 winner has won the series xx% of the time and so on...Can someone help?
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