Stanley Cup playoffs

The Stanley Cup playoffs is an elimination tournament in the National Hockey League consisting of four rounds of best-of-seven series. The first three rounds determine which team from each conference will advance to the final round, dubbed the Stanley Cup Final.

Format
The first round of the playoffs, or Conference Quarterfinals, consists of four match-ups in each conference, based on the seedings (# 1 vs. # 8, # 2 vs. # 7, # 3 vs. # 6, and # 4 vs. # 5). In the second round, or Conference Semifinals, the top remaining conference seed plays against the lowest remaining seed, and the other two remaining conference teams pair off (unlike the NBA, for example, where the 1–8 winner always plays the 4–5 winner, regardless of who wins). In the third round, the Conference Finals, the two remaining teams in each conference play each other, with the conference champions proceeding to the Stanley Cup Final.

For the first three rounds, the higher-seeded team has home-ice advantage (regardless of point record). In the Stanley Cup Final, it goes to the team with the better regular season record. The team with home-ice advantage hosts Games 1, 2, 5 and 7, while the opponent hosts Games 3, 4 and 6 (Games 5–7 are played "if necessary").

From the 1981–82 season to the 1992–93 season, the playoff format was completely different. Each of the league's two conferences were divided into two divisions, and the top four teams in each division advanced to the playoffs. Also, instead of the top-ranked team playing the eighth-place team in the conference in the first round, the first-place team played the fourth-place team in each division, and the second-place team played the third-place team (the Division Semifinals). In the second round, the two winning teams in each first-round series would face each other for the divisional championship (the Division Finals). The divisional champions in each conference would play one another in the third round (the Conference Finals) for the right to advance to the Stanley Cup Final. This structure is still used for determining the teams in the playoffs in the American Hockey League.

History
The National Hockey League has always used a playoff tournament to determine its champion, generally opening up its playoff games to a much larger number of teams, including those with a losing regular season record in some years.

From the NHL's inception to 1920, when ownership of the Stanley Cup was shared between the NHL and the Pacific Coast Hockey Association the regular season was divided into two halves, with the top team from each half moving on to the league finals, which was a two-game total goals series in 1918 and a best-of-seven series in 1919. In 1920, the Ottawa Senators were automatically declared the league champion when the team had won both halves of the regular season. The two halves format was abandoned the next year, and the top two teams faced off for the NHL championship in a two-game total goals series.

At the time, the NHL champion would later face the winners of the PCHA and, from 1921, the Western Canada Hockey League in further rounds in order to determine the Stanley Cup champion. During this time, as the rules of the NHL and those of the western leagues differ (the main difference being that NHL rules allowed five skaters while the western leagues allowed six), the rules for each game in the Stanley Cup Finals alternated between those of the NHL and the western leagues. Before the WCHL competed for the Stanley Cup, the Stanley Cup Finals was a best-of-five series. Following the involvement of the WCHL, one league champion was given a bye straight to the finals (a best-of-three affair starting in 1922), while the other two competed in a best-of-three semifinal. As travel expenses were high during these times, it was often the case that the NHL champions were sent west to compete. In a dispute between the leagues in 1923 about whether to send one or both western league champions east, the winner of the PCHA/WCHL series would proceed to the Stanley Cup Finals while the loser of the series would face the NHL champions, both series being best-of-three.

In 1924 the NHL playoffs expanded from two to three teams (with the top team getting a bye to the two-game total goal NHL finals), but because the first-place Hamilton Tigers refused to play under this format, the second and third place teams played for the NHL championship in a two-game total goals affair. The Stanley Cup Finals was returned to the best-of-five format the same year.

NHL takes control of Stanley Cup
With the merger of the PCHA and WCHL in 1925 and its collapse in 1926, the NHL took sole control of the Stanley Cup, and from this point the NHL playoffs and the Stanley Cup playoffs are considered synonymous. The NHL was subsequently divided into the Canadian and American divisions until the 1937-38 season. For 1927, six teams qualified for the playoffs, three from each division, with the division semifinals and finals being a two-game total goals affair and the Stanley Cup Finals a best-of-five affair. In 1928, the playoff format was changed so that the two teams with identical division ranking would face each other (i.e. the first place teams played each other, the second place teams play each other, and likewise for the third place teams). The first place series was a best-of-five affair, with the winner proceeding to the best-of-three Stanley Cup Finals, while the others was a two-game total goals series. The winner of the second and third place series played each other in a best-of-three series, with the winner earning the other berth to the Stanley Cup Finals. This format had a slight modification the following year, where the semifinal series became a two-game total goals affair and the Stanley Cup Finals became a best-of-five series. The two-game total goals format was abolished in 1937, with those series being changed to best-of-three affairs.

Original Six era
The 1938-39 season saw the reduction of teams from 10 to 7, and with it an end to the Canadian and American divisions. The Stanley Cup playoffs saw the first and second place teams play against each other in a best-of-seven series for one berth in the Stanley Cup Finals, while the third to sixth place teams battled in a series of best-of-three matches for the other berth (with the third place team battling the fourth place team, and the fifth place team against the sixth place team). The playoff format introduced in the 1938-39 season had a best-of-seven Stanley Cup Finals, which still stands today.

The 1942-43 season saw the removal of the New York Americans, and thus the six remaining teams formed the Original Six. During this era, the playoff format went unchanged, with the first and third place teams battling in one best-of-seven semifinal, while the second and fourth place teams battled in the other best-of-seven semifinal. During this time, Detroit Red Wings fans often threw an octopus onto the ice as a good luck charm, as eight wins were required to win the Stanley Cup.

Expansion era
The Modern Era expansion saw the number of teams double from six to twelve in the 1967-68 season, and with it the creation of the Western and Eastern Conferences. The playoff format remained largely the same, with all series remaining best-of-seven, and the Western and Eastern Conference champions battling for the Stanley Cup. The 1970-71 season, because of fan demand, brought forth the first interconference playoff matchup outside of the Stanley Cup Finals since the pre-war expansion, which had the winner of the 2 vs 4 matchup in one conference take on the winner of the 1 vs 3 matchup in the other conference for a berth in the Stanley Cup Finals. The following year had one minor change to its playoff format: a stronger team would face a weaker opponent. Thus, instead of a 1 vs 3 and 2 vs 4 matchup in the first round, the first round had a 1 vs 4 and 2 vs 3 matchup. This practice of having stronger teams facing weaker opposition would continue to the present day.

The 1974-75 seasons saw another change to its playoff system to accommodate the league of now 18 teams, 12 of which qualified for postseason berth. The top team from each division would earn byes to the Stanley Cup quarterfinals, while the second and third place teams from each division started their playoff run from a best of three preliminary round. In each round of the playoffs, the teams remaining were seeded regardless of divisional or conference alignment, with the preliminary-round series being a best-of-three affair while the remainder of the series remained best-of-seven. The 1977-78 season had one minor change in its playoff format: although the second place finishers from each division would qualify for the preliminary round, the four playoff spots reserved for the third-place teams were replaced by four wild-card spots - spots for the four teams with the highest regular-season point total but which did not finish first or second in their divisions.

NHL-WHA merger
With the absorption of four teams from the World Hockey Association in the 1979-1980 season, a new playoff system was introduced where 16 of the league's 21 teams would qualify for postseason play. The four division winners would qualify for the playoffs while twelve wildcard positions rounded out the sixteen teams. At the beginning of each round the teams were seeded based on their regular season point totals, with the preliminary round being a best-of-five series while all other playoff series were best-of-seven.

Divisional playoffs
The 1981-1982 season brought forth the return of divisional matchups, with the top four teams from each division qualifying for the postseason play. Division champions would be determined, followed by the Conference champions, who would meet in the Stanley Cup Finals. The division semifinals was a best-of-five affair until the 1986-87 season, when it became a best-of-seven series, while all other series remained best-of seven.

Since 1993
The 1993-94 season brought forth the change in the playoff format that would result in the format being used today. The league revamps its playoff structure to become conference, rather than division-based. The top eight teams in each conference qualify for the playoffs. The division first-place teams are seeded first and second in the playoffs and receive home ice advantage for the first two rounds (in essence, they keep their seeding). The next best six in each conference qualify also. All teams play in the first round, seeded 1 versus 8, 2 vs. 7, 3 vs. 6, 4 vs. 5. All series are best-of-seven, but the arrangement of home games is changed for Central and Pacific division teams. Instead of the normal 2–2–1–1–1 rotation, series involving those divisions are 2–3–2, with the higher seeded team having the option of starting play at home or on the road. After each round, teams are reseeded to play a conference semi-final, then a conference final. The conference winners play in the Stanley Cup Final (which remains a 2–2–1–1–1 format)

In 1999 the league was re-organized into two conferences of three divisions apiece. The qualifiers remain sixteen, but the seeding changes. The first-place team in every division qualifies and is seeded first through third for the playoffs. Of the other teams in each conference, the top finishers qualify for the fourth through eighth seedings. All teams play in the first round, seeded 1 versus 8, 2 vs. 7, 3 vs. 6, 4 vs. 5 by that criteria. For the conference semi-finals and finals, the winning teams follow the same criteria. The conference winners play each other for the Stanley Cup in the Final. Home ice advantage is determined by highest seed in the first 3 rounds and by regular-season points of the two teams in the Stanley Cup Finals.