Playoff format

There are several different Playoff formats used in various levels of competition in sports and games. Some of the most common are the single elimination, the best-of- series, the total points series, and the round-robin tournament.

Single elimination
A Single elimination ("knockout") playoff pits the participants in one-game matches, with the loser being dropped from the competition. Single elimination tournaments are much more common in individual sports like tennis. In most tennis tournaments, the players are seeded against each other, and the winner of each match continues to the next round, all the way to the final.

Of the big four American sports leagues, only the National Football League uses this system. Its regular seasons are much shorter (16 games) than those in the other sports (from 82 to 162 games), and the difference in quality between teams is believed to be more quickly discernible; the rigors of individual games, held only once per week, also preclude the possibility of longer playoff series. Six teams are seeded from each conference, with the top two getting a first-round "bye" (a free pass to the second round). The remaining teams pair off, with the higher-seeded team hosting. The winners play the teams that received byes, and the winners of those matches face each other to determine who will represent each conference in the Super Bowl. The winner of that game wins the championship.

In both the men's and women's NCAA college basketball tournaments, 64 teams are seeded into four brackets of 16 teams each. (On the men's side, the 64th place team and a 65th team play each other in a play-in game to determine the final participant.) The #1 team plays the #16 team in each bracket, the #2 plays the #15, and so on. Theoretically, if a higher ranked team always beats a lower ranked team, the second game will be arranged #1 vs. #8, #2 vs. #7, etc.; the third will be arranged #1 vs. #4, #2 vs. #3; the fourth will be arranged #1 vs. #2. If for instance #9 beats #8 in the first game, the #9 will simply take the theoretical spot of #8 and play #1. Winners advance through each round, changing cities after every two rounds. The Final Four teams, one from each bracket, play each other in the last weekend, with the winner of the final two being awarded the championship.

Association football often uses single elimination to determine finalists and winners. Major League Soccer's second and final rounds of its playoffs use a single elimination format, though the first round is a total points format. The FIFA World Cup also uses knockout rounds after a group stage of 32 teams divided into 8 groups of 4 determines who advances to them.

Example
As it was used in the 2007 AFC Asian Cup knockout stage:

Note that a third-place playoff was held prior to the final. The losers of the semifinals played in that game. The losing semifinalists were still in effect "eliminated" from contending for the championship.

Double elimination
A double elimination format is used in most NCAA and high school baseball and softball tournaments in the United States.

The format changes depending on the number of teams per bracket, but most major collegiate baseball conferences with the format send only the top eight teams, or a mix of top teams plus the winners of a single elimination qualifier tournament, to their conference tournament.

The NCAA baseball and softball tournaments have used the format since its inception for regional and College World Series play.

In the current NCAA tournament format for four teams, the #1 seed plays the #4 seed ("Game 1"), and the #2 seed plays the #3 seed ("Game 2") on the first day of regional tournaments, and the first and second days of the College World Series (where the second bracket games are known as "Game 3" and "Game 4", respectively).

On the second day or series (third and fourth days at the College World Series), the losers play in the morning to determine who is eliminated ("Game 3" in regional, "Games 5" and "Game 7" in College World Series play), and who advances to the third game of the day. The winners ("Game 4" in regional, "Game 6" and "Game 8" in College World Series) play to determine who advances to the final on the third day.

In NCAA regional games, the loser of this game plays the winner of the morning game that evening ("Game 5") to determine who plays in the final.

In College World Series play, because the bracket teams play on alternating days, these games ("Game 9" and "Game 10") are played on the fifth day.

In NCAA regional games, the third day will feature the regional championship ("Game 6"). If the winner of Game 4 defeats the winner of Game 5, the winner advances to the Super Regional. Until the 2005 tournament, if the winner of Game 5 defeats the winner of Game 4, the two teams would meet again in Game 7 thirty minutes later to determine which team advances to the Super Regional.

However, with a concern that some teams were playing four games in two days, the NCAA made a rule change in 2005 to equalise the disadvantage of the winner of Game 5 by stating should the winner of Game 5 win Game 6, Game 7 would be played on a fourth day.

In the College World Series, on the sixth day, the winner of Game 9 plays the winner of Game 7 ("Game 11"), and the winner of Game 10 plays the winner of Game 8 ("Game 12"). If the winner in Game 7 wins Game 11, and/or the winner of Game 8 wins Game 12, such winners advance to the best-of-three final. If the winner of Game 9 defeats the winner of Game 7, and/or the winner of Game 10 defeats the winner of Game 8 the two teams would play again on the seventh day in Games 13 and 14, respectively, if they are needed, to determine who advances to the final.

Example
As it was used in the Mideast regional of the 1975 NCAA Division I Baseball Tournament:

Best-of formats
The "best-of" formats refers to a head-to-head competition where the two competitors compete to first win the majority of the games allotted to win the "series". If a competitor wins a majority of the games, the remaining games may be discarded. This is a modification of the single elimination tournament to allow more matches to be held.

Best-of-three playoff
A best-of-three playoff is a head-to-head competition between two teams in which one team must win two games to win the series. Two is chosen as it would constitute a majority of the games played; if one team wins both of the first two games, the third game is not played.

The first use of the best-of-three playoff was in Major League Baseball; the National League authorized such a playoff to be held if two teams ended the season in a tie for first place; the American League used a single game in this situation. Since both leagues have used only a one-game playoff for all playoff positions which are tied if only one team can advance to the playoffs. Since, a tie-breaker based on season performance can be used only to seed teams. Recently, there has been talk of Major League Baseball possibly adding a second wild card playoff berth in each league, then having the two wild cards in each league play each other in a best-of-three series to start the postseason, with the six division winners drawing byes. Its prospects for passage by the sport's club owners, however, appear remote.

Both the NBA and NHL once used best-of-three playoffs (often referred to as "mini-series"), but today neither league does: Pro basketball first adopted the best-of-three playoff for first-round play starting with its inception as the Basketball Association of America in 1946 (changing its name to the NBA three years later) and retaining it through the 1959–60 season; the league resumed its use of the best-of-three first-round series in 1974–75, but abolished it again in 1983–84 when the number of teams qualifying for its postseason tournament was increased to 16 (ten teams had qualified during the first two years of the aforementioned period, this number being expanded to twelve in 1976–77; in both instances some of the highest-ranking teams did not participate in the best-of-three round, drawing byes and automatically advancing to the second round, which was best-of-seven, as were all subsequent rounds).

In ice hockey, the best-of-three format was one of two possible types of series that could be held to determine the winner of the Stanley Cup (the other being a two-legged playoff series), and it was used in lower rounds in the National Hockey League up until the Original Six era. The best-of-three series in the modern era was first used in the first-round of the Stanley Cup playoffs beginning with the 1974–75 season; at that time, the number of NHL playoff teams had been increased to twelve from the previous eight. The format which then took effect called for the first three finishers in each of the league's four divisions to enter the postseason, but the first-place teams drew byes and did not play any best-of-three series; the postseason then proceeded as the NBA's did, with the second and all later rounds being best-of-seven. This remained the case until the 1979–80 season, when the NHL expanded its playoff field to 16 after absorbing four teams from the defunct World Hockey Association in a semi-merger, whereupon the byes were abolished and all 16 qualifying teams participated in the first round, which was lengthened to best-of-five. In both the NBA and NHL, the team with the higher finish during the regular season played the first and (if necessary) the third games of the series at home, with the lower-ranked team hosting the second game.

The only top-level professional league in the United States that now uses a best-of-three format for its playoffs is the WNBA. The women's game is the only pro league that forces the team with the higher record to travel to the lower seed's home court for game 1, then play the final game(s) at home. Perhaps because of this perceived inequity, in 2005, the league switched the WNBA Finals to a best-of-five playoff format.

NCAA baseball has two best-of-three series in their 64-team playoff format. Starting in 1999, when the tournament expanded from 48 teams (eight regionals of six teams each) to 64 teams (sixteen regionals of four teams each), the NCAA introduced the "super regional", in which regional winners play a best-of-three series with the series winner advancing to the College World Series. If a regional winner is also a national seed, it is guaranteed to host the super regional; if no national seed makes a particular super regional, the NCAA puts hosting rights up for bidding between the competing schools. In 2003, the College World Series changed from a one-game final to a best-of-three series.

The Euroleague, the primary Europe-wide club competition in basketball, introduced a quarterfinal round for the 2004–05 season which originally employed a best-of-three format; starting with the 2008–09 season, the quarterfinal round became best-of-five. This is the only point in the Euroleague where a playoff series is used; all earlier rounds are conducted in a league format, and the quarterfinal winners advance to the Final Four, where all games are one-off knockout matches.

In a modification of the best-of-3 format, the collegiate basketball leagues in the Philippines (notably the NCAA and the UAAP), the playoffs consist of two best-of-3 rounds. In the Semi-Finals, the two top seeds receive twice to beat advantage, wherein they receive an automatic 1-0 advantage, the lower seeded team needs to beat its opponent twice, while the higher seeded team only needs a single victory. The survivors face of in a best-of 3 Finals. A full double-elimination tournament gives the lone undefeated team this so-called twice to beat advantage.

In the FIBA Oceania Championship, the best-of-three series is used if only both Australia and New Zealand play in the tournament. If a team wins the first two games, the last game may still be played. If other teams participate, a regular round-robin or multi-stage tournament is used.

The best-of-3 playoff system was also used in the Brazilian Football League for the 1998 and 1999 seasons quarterfinals, semifinals and finals. However, since matches could end in a draw, this system had a few modifications. If no team could win two games, the team with most victories would qualify. If the two teams had one victory, the team with the best goal difference would qualify. If the goal difference was the same, the team with the best regular season campaign would qualify. A interesting fact is that during the 1998 season, all the rounds were decided in three games.

In tennis, the best-of-3 format is the format used in the Wimbledon except for matches of the Gentlemen's Singles and Gentlemen's Doubles competitions, which are played in the best-of-5 format. Also the 35 and over Gentlemen's Invitation Doubles and the 35 and over Ladies' Invitation Doubles of the Wimbledon are both round-robin tournaments.

Another use of name
Often, when a best-of-7 series is deadlocked at 2-2, the series is then referred to as a "best-of-3". In these cases, the first team to get their next 2 wins advances.

Best-of-five playoff
A best-of-five playoff is a competition between two teams head-to-head which must win three games to win the series. Three is chosen as it would constitute a majority of games played; if one team has won three games before all five games have been played, the games that remain are omitted.

At present, only one American men's professional sports body - Major League Baseball - makes use of the best-of-five playoff, doing so in its first round, known as the Division Series. At one time, however, the League Championship Series was best-of-five, from its birth with both leagues' realignment into two divisions in, and continuing until this round was lengthened to best-of-seven in. When the wild card was first used in (it was created for the  season, but that year's entire postseason was canceled due to a players' strike), the best-of-five format was authorized for the new Division Series, in which eight teams participate.

During the time that the League Championship Series was best-of-five, a "2-3" format was used, with one team hosting the first two games, the other the last three (these respective roles alternating between the Eastern and Western Division champions regardless of which one finished with the better regular-season record). This procedure was repeated at first when the best-of-five Division Series was added in 1995 (except that two of each league's now three division winners hosted three games and the wild card could never do so), but starting in the home-field advantage was awarded to the two division winners in each league that had the best records; also in 1998, the "2-2-1" format was instituted, the team with the home-field advantage being given the first, second and fifth games at home instead of the third, fourth and fifth.

The National Basketball Association and National Hockey League both formerly used best-of-five series, the NBA in its second round prior to the season, and in the first round from  through, and again from  until lengthening it to best of seven starting in , and the NHL for its first-round series beginning with the  season and lasting until that league increased its first round to best-of-seven in. Unlike in baseball, in both NBA and NHL best-of-five series the higher regular-season finisher always hosted the first, second, and (if necessary) fifth games.

As of 2005, the Women's National Basketball Association now uses a best-of-five format for its championship series. However, the previous two WNBA playoff rounds are best of three.

Historically, most European domestic basketball leagues have used a best-of-five format in their championship series. The main long-standing exceptions are the Israeli and French leagues, which use one-off finals; the Adriatic League (former Yugoslavia), which has changed from a one-off final to a best-of-three final back to a one-off final in recent years; and the Lithuanian, Polish and Turkish leagues, which use a best-of-seven format. Italy has gone to a best-of-seven final effective with its 2008–09 season. The Euroleague quarterfinal round expanded to best-of-five from best-of-three starting in the 2008-09 season.

Best-of-seven playoff
A best-of-seven playoff, also known by the name seven-game series, pits two teams against each other for as many games (or sets) as needed for one team to win four games (or sets). It is by far the most common playoff format in the major North American sports. It is not necessary for the four games to be consecutively won. Since each game must be won by one team or the other there can be at most seven games in a series. Before the advent of lighting in ballparks ballgames often ended tied because it was too dark to play anymore; in the modern era, a much less common way of ending a ballgame is going past the curfews. Therefore, the series can in practice last eight games, as in the 1912 World Series. This format is currently used in the National Basketball Association and the National Hockey League for all their playoff series. Major League Baseball uses this format only for the League Championship Series and the World Series, using the "2-3-2" format, with two games at the home stadium of one team, the next three games (the fifth, if necessary) at the home stadium of the other team, and the final two games (if necessary) at the home stadium of the first. (The first round Division Series use a five-game series format.)

The National Hockey League uses this format for its league championships and Stanley Cup playoffs, but uses the "2-2-1-1-1" format, alternating the first two games at the home-ice team's home rink, the next two at the second team, and then alternating venues for the fifth, sixth and seventh games (if necessary). The National Basketball Association also uses the "2-2-1-1-1" format for every series through the conference finals, switching to the "2-3-2" format for the NBA Finals, which they have used since 1985.

Both the "2-3-2" and "2-2-1-1-1" formats are situated such that if a team "sweeps" the series (wins 4-0), it will win two games at home, and two games away.

As noted earlier, the Italian, Lithuanian, Polish and Turkish basketball leagues use a best-of-seven format in their championship series. The Turkish playoff has one unique feature. If one team in the championship series (or, for that matter, in any playoff series) defeated its final opponent in both of their regular-season games, the winning team is granted a 1-0 lead in the series, and the series starts with Game 2.

The Chinese Basketball Association also uses a best-of-seven format in their championships series.

Best-of-nine playoff
A best-of-nine playoff pits two teams head-to-head which must win five games to win the series. Five is chosen as it would constitute a majority of the games played. If one team has won five games before all nine games have been played, the games that remain are omitted.

In Major League Baseball, the World Series was conducted as a best-of-nine playoff in its first year of existence in 1903, then again for three years beginning in 1919, the year of the "Black Sox scandal."

The Western Hockey League used the best-of-nine playoff series for the Western Division playoffs from the 1983-84 season through the 1990-91 season because of the unequal division alignment of the league at this time. The Eastern division had eight teams: six of which qualified for the playoffs. The Western division only had six teams: four of which made the playoffs. Because of this, Eastern division had 3 rounds of playoffs (two teams receive a first round bye), while the Western division only had two rounds of playoffs. The east played a best-of-five, best-of-seven, best-of-seven format for the three rounds while both rounds in the Western division playoffs were best-of-nine. This was used so that both divisions would finish their playoffs at approximately the same time. The WHL Championship Series was a best-of-seven. These best-of-nine series went the full nine games on two occasions, with Portland defeating New Westminster in 1984 and Spokane in 1986.

The Quebec Major Junior Hockey League used the best-of-nine playoff series for the 1986 playoffs.

Higher number of games
In snooker, a player must win a certain number of frames to win a match, often nine (best-of-17) or more. Again, if one player wins nine frames before all 17 are played, the rest are omitted. The world championship final is currently decided in a best-of-35 match.

In 9-ball, a player must win a certain number of racks to win a match. In the WPA World Nine-ball Championship, nine racks are needed to win in the early stages, ten to eleven in the latter stages, and 17 in the final. Same with snooker, if one player wins nine frames before all 17 are played, the rest are omitted.

Total points series (aggregate)
Various formats, including two-legged ties and total points series pair off participants in a number of games (often two), with the winner being determined by aggregate score: the winner being the one who scores the most points/goals etc over the series of games. Two-legged ties are common in association football, and were used in NHL playoff series until 1937.

In 2004, NASCAR adopted a total points playoff of a different stripe, creating a "Chase for the Cup" that allowed a golf-style cut of the high ten or 400 points of the leader, whichever is greater, to compete for the championship in the last ten races. Effective with the 2007 season, the Chase was expanded to include the top 12 drivers after 26 races. The points of the drivers in the cut are elevated far beyond those of the pack (from 2007 onward, each Chase driver receives 5,000 points, with a 10-point bonus for each race won prior to the Chase), and the driver in that group with the most points after the final ten races wins the Sprint Cup.

In November 2005, the PGA Tour announced that a similar total points playoff would be used to lead up to the PGA Championship, starting in 2007. The player with the most points at the end of the year would take home the FedEx Cup.

Prior to the 1986 Playoffs, the Canadian Hockey League (especially the Ontario Hockey League) used the point series, to determine, which team would advance. In those situation, where the higher seeded host in odd number of game (game #1, 3, 5, 7), while the other team host the even number (game #2, 4, 6, 8). There would be no overtime, except for the deciding game, because a tie in the last game, of the series would not declare a series winner, so should that happens, there would be a sudden-death overtime, with the winner getting 2 points, and the losing team get nothing.

The game show Jeopardy! uses a two-game series in the final round of its tournaments. Each game is played separately (i.e., money from day one cannot be wagered on day two), and the money is added together to determine the winner. The only exception to this was in the Jeopardy! Ultimate Tournament of Champions, when the two semifinal matches were both two-game series, and the final was a three-game series.

Example
As it was used in the 2006–07 UEFA Champions League knockout stage:

''Bayern Munich 4–4 Real Madrid on aggregate. Bayern Munich won on away goals.''

Round robin
In a round-robin tournament, all playoff contenders play each other an equal number of times, usually once or twice (often called a "double round-robin"). This is a common format for football. In the FIFA World Cup, teams are organized into eight pools of four teams, playing each other once and ranked by points earned through wins (3 points) and draws (1 point). The top two teams advance out of each pool to the knockout phase where the top team from each pool face second-placed team from a different pool.

Recently, continental club football tournaments have included round robin formats, such as the UEFA Champions League from the 1992/93 season, UEFA Cup from 2004/05, and the Asian and African Champions Leagues. Teams are seeded such that strongest teams should not meet until the end. In the UEFA Champions League, 32 teams are divided into eight groups of four. The group winners and runners-up advance to a two-game, total goals round, the eight third-placed teams move into the UEFA Cup third round, and the eight fourth-placed teams are eliminated.

In basketball, the Olympics also uses a round robin of the same nature, going to single elimination after the first round. The Euroleague has two double round-robin phases. The first is a "Regular Season" in which the 24 teams are divided into four groups of six (as of the 2008-09 season). The four top teams in each group advance to a "Top 16" phase in which the teams are divided into four groups of four each. The top two teams from each Top 16 group are then paired in four best-of-five quarterfinal series, with the winners advancing to the single-elimination Final Four.

Round-robin tournaments are also used in rugby union, curling, and many amateur or lower-division basketball, football, and hockey tournaments.

In 1992, Little League baseball went to a round-robin tournament in the first round instead of single-elimination. In 2001, the tournament expanded to 16 teams and stayed with a round-robin for the first round, but cross-bracketed single elimination for the second round before the two winners of those games advanced to the region final.

In Major League Baseball, the term "round robin" was used with regard to the possibility of a 3-way tie for the National League pennant in 1964. The Philadelphia Phillies had had a 6 1/2 game lead with 12 games left in their regular schedule, but then lost 10 games in a row, so that the season went into its last day with 3 teams still having a chance for the NL pennant. As it turns out, the St. Louis Cardinals defeated the New York Mets on that day to take the NL pennant with no playoff; the reverse of that outcome would have left the Cardinals, the Phillies, and the Cincinnati Reds in a 3-way tie.

Example
As it was used in the "Super Six" round of the 1999 Cricket World Cup: Teams in shaded in blue advance to the knockout stage.

Associated concepts
As discussed above, leagues also offer innovations in order to give advantage to teams that performed better in the regular season, such as reseeding and home advantage.

Reseeding
In tournaments where participants are seeded, in order to ensure that the strongest remaining team faces the weakest team, the participants are "reseeded" at each round; the tournament bracket is not fixed, where potential matchups can be readily determined up to the final. For example, in a regular 8-team bracket, the teams that will meet at the second round will be the winner of the #1 vs. #8 going up against the winner of #4 and #5, and the winner of #2 and #7 going up against the winner of #3 and #6. If the #5 and the #7 teams won in the first round, the second round matchups will be #1 vs. #7 and #3 vs. #5, instead of #1 vs. #5 and #3 vs. #7.

Notable tournaments that employ this rule are the NFL Playoffs and the Stanley Cup Playoffs. Note that reseeding does not come into play if there are only 2 rounds of competition.

Home advantage
In team sports, the "hometown advantage" refers to the phenomenon when certain teams (usually the higher-seeded teams) are afforded more games that can be played at their home arena/stadium than their opponent's. This is predominant in the best-of series where there are more games played in a team's arena/stadium than the other, and in single-elimination tournaments where the single game is disputed in a team's stadium. In a best-of series, a team can "lose" their home advantage if the visiting team wins the first game. Home advantage can be regained or lost in the course of the series.

As discussed above, a team can clinch the "home advantage" in a variety of ways:
 * Clinching the higher seed (MLB, NHL and NFL)
 * Winning more games than the opponent, but not necessarily clinching the higher seed (NBA)

In best-of series, the order of arenas/stadiums in which the games are played at also affects the home advantage. In the NBA, the first three rounds are done in a 2-2-1-1-1 format, that is, the team with the home court advantage plays games 1-2, 5 and 7. This ensures that the team with the home court advantage never trails assuming every game is won by the home team. In the NBA Finals, the games are scheduled in the 2-3-2 format (the team with the home court advantage plays games 1-2 and 6-7 in their home court), which can theoretically allow the team with the home court advantage to trail in the series (although that will require the team with the home court advantage to lose the middle three games, which has only happened twice since the format was introduced in 1985).

In the MLB's World Series, the team that came from the league that won the All-Star Game is awarded with the home field advantage. In the Stanley Cup and NBA Finals, the teams with the higher regular season record receives the home advantage.

In two-legged ties such as the UEFA Champions League, although it is said that the two teams play an equal amount of games in their home stadium, the team playing the second game in their home stadium has a distinct advantage, ((Fact|date=November 2009}} such as the resolution of ties will be at their stadium.

In games done on neutral venues, a team may still be afforded the privileges of the "home team" such as selecting which side to play first or choosing the side of the coin in coin flips. In most instances, this privilege is determined either by a drawing of lots (UEFA Champions League) or by rotation among the groupings of the different teams (NFL).

In the Nippon Professional Baseball's postseason games (excluding Japan Series) since 2004, the team having a better position in regular position will be hosting all the games. In addition, since 2008, the League Champion will have a 1-win advantage in the 2nd stage of Climax Series (best-of-7 which actually played for 6 games).