It's time for the Aussie Rules football playoffs, giving us a chance to examine Australian playoff systems, which have several unusual elements.
There are 17 teams in the Australian Football League, and the top 8 make the playoffs. In a typical North American playoff system, that would lead to the quarterfinal matchups 1-8, 4-5, 2-7, and 3-6. For Aussie rules, though, the matchups are 1-4 and 2-3, known as the qualifying finals, and 5-8 and 6-7, known as the elimination finals.
After the first round, the qualifying finals winners get a week off. The losers drop down to face the winners of the elimination finals in what are called the semifinals. (The losers of the eliminations finals, as the name implies, are eliminated.)
The two "semifinal" winners now move on to face the qualifying finals winners in the "preliminary finals," which is what the rest of us call a semifinal. The two winners face off in the grand final to determine the champion.
(That oddly named "semifinal" is confusing, but in Australian sports there are a number of things with slightly odd names to get used to. The standings or table is referred to as a "ladder," for example.)
Essentially, what the Aussie Rules system does is give the top four teams a significant edge over the fifth through eighth teams in reaching the final four. A 5-8 team must win twice to get there, while a 1-4 team must only win one of two games.
Other Australian sports use similar systems. In soccer, 6 of 11 teams make the playoffs. The initial matches are 1-2 (a two-game total goals series), 3-6 and 4-5 (single games). The 3-6 and 4-5 winners play each other, and the winner of that game takes on the 1-2 loser. The winner of this "preliminary final" meets the 1-2 winner in the grand final.
This system provides a huge edge to teams 1 and 2, who must win only one series to make the grand final. (And losing that series, still have a chance to make the final with a win in the preliminary final.)
A 3, 4, 5 or 6 team, by contrast, must win three straight games to make the final.
One flaw in this system is that it kind of blows its best game too early by matching 1 and 2 in week one. Even if those two teams eventually also make the grand final, it may seem anticlimactic.
Hold on, because rugby league is even more confusing. Of the 16 teams in the league, 8 qualify for the playoffs. The matchups are traditional. 1-8, 4-5, 2-7, 3-6. Then it gets crazy.
The two top-ranked winners of these games get a bye. The other two winners are drawn against the two highest ranked losers for what are called semifinals, while the two lowest ranked losers are knocked out. The winners of these semifinals take on the two teams with byes in the "preliminary finals" and the winners there meet in the grand final.
An example might clear this one up a bit. In 2010, the 1st and 4th seeds won their opening matches and earned byes as the top-ranked winners. But 6 upset 3, and 7 upset 2. So the two lowest ranked losers (8 and 5) were knocked out, and the "semifinals" matched the remaining teams, 3-7 and 2-6. 3 and 6 were the winners there, and faced bye teams 1 and 4 in the preliminary finals, and 1 beat 6 in the grand final.
One oddity of this system is that it is important what order the first round is played in. It always must be 4-5, 3-6, 2-7, and then 1-8. Imagine if the order were the opposite, say, and 1 and 2 won their games. Now we know that 1 and 2 are the highest seeded winners and will get the byes. Likewise we know that 7 and 8 are the lowest-seeded losers and will be eliminated. The 3-6 and 4-5 games are now meaningless. Only if those games are played first can it be assured that teams play knowing that the result may have an effect. (For example, 6 must try had to beat 3 in its game if it knows that 8 or 7 might win and knock it into the two lowest-ranked losers.)
The common thread of all these systems is giving higher-ranked teams a greater chance of reaching the later rounds, above and beyond the home-field advantage that American sports generally provides. FRB is generally quite receptive to playoff ideas from other lands, but he doesn't think these systems would work in the U.S.
One other thing Australian sports have in common is a single regular-season table, with no regional divisions. So at the end of the regular season we have a pretty fair notion that 2 is deservedly ranked above 3, and 4 above 5. Therefore we can give a generous reward to the better-seeded team with a high degree of confidence that we're being fair. In the U.S., divisions and unbalanced schedules mean we don't have as great a sense which teams have earned a higher ranking. Maybe we can give home-field advantage to a 11-5 team from the NFC Central over a 10-6 team from the NFC East, but do we really feel comfortable giving the 11-5 team an extra chance to make the final as well?
Not to mention the confusion. FRB thinks it would probably take about a generation for most fans to keep the preliminary finals, semifinals and qualifying finals straight.