How the All Blacks are only just world No 1

[The InnFORCEr]

JOHN HARTEVELT AND ANDY FYERS
Last updated 10:36 08/10/2014



The All Blacks were unbeaten for 22 test matches in a row. They're the world champions and still on a 36 test match winning streak at home since 2009. They're streets ahead of the competition, right? Well, not exactly, according to the latest International Rugby Board (IRB) rankings.

After a narrow loss at the weekend, the All Blacks' lead at the top of the official rankings has been cut to about two points.

The All Blacks have won 90 per cent of their matches since 2010 and have 93.81 points on the IRB scorecard. By comparison, the Springboks have won only 68 per cent of their matches over the same period, but have 90.41 points in the latest rankings. How can this be?

The IRB awards points for its rankings game by game. It's kind of complicated (a detailed explanation is online here) but basically, the system is designed such that it's tough for the top team to pull away when it's winning, but easier for it to quickly fall back when it loses.

A win over a higher ranked team is worth more points. A win over a lower ranked team is worth less - sometimes much less. For example, in June, the Wallabies beat France three times in a row but gained only 0.06 points in the rankings. A single win over higher-ranked South Africa in Perth last month, however, boosted Australia by 0.91 points.

This makes it difficult for the All Blacks, because there has been no team ranked above it since November 2009.

Two wins over Argentina and one each over Australia and South Africa between August 23 and September 27 boosted New Zealand's ranking by a total of only 0.33 points.

By itself, the win over the Springboks on September 13 was worth a piffling 0.19 of a point. But when the Springboks beat the All Blacks in Johannesburg last weekend, it lifted South Africa by a whopping 1.14 points.

Another problem for the All Blacks is that their winning streak at home is worth very little. The home team in every clash is handicapped in the IRB rankings system, so winning away is extra valuable and winning at home is not worth much.

When the home team handicap is combined with how far ahead of the competition the All Blacks are, it can lead to disappointing results. For example, three wins over England in June was worth nothing at all to the All Blacks' ranking. England did not lose any points as a result of the series whitewash, either. On the other hand, when England beat the All Blacks on their home ground, at Twickenham, in December 2012 they claimed a huge 2.8 point gain. This was mostly a reflection of the 11.8 point gap between the teams before the game started, which was suddenly narrowed to a 6.2 point gap after the result. The swing would have been even greater if it had been a home test for the All Blacks.

Although the points system may seem tough on the All Blacks, they have seldom been toppled from the top spot. Since October 2003, it's had 482 weeks at the top, 91 weeks in second and one in third (that was after a particularly painful World Cup defeat in November 2003).

The IRB says it spent years devising its ranking system, drawing on an extensive database of international matches going back to 1871. It judges its accuracy by how well it predicts results.

In our graphic below, the IRB ranking points for the top countries back to October 2009 are shown. To isolate the results for particular countries, click on names in the key to omit them.

http://www.stuff.co.nz/sport/rugby/a...ust-world-No-1

[Sheikh]

Three things spring to mind:

1) The All Blacks are complaining that that they are being penalised for being too successful?

2) How does a points difference between 93.81 and 90.41 equate to 'about two points'? - ETA: Answer, the All Blacks only have 92.6, not 93.81!

3) The points calculation is actually easy:

Home side has an IRB ranking of 'A' points
Away side has an IRB ranking of 'B' points

Give the home side 3 points for home field advantage, ie, A+3

Calculate the points difference between the home and away side, ie, (A+3) - B, or B - (A+3). If (A+3) - B is greater than 0 the home side is the 'better' team; otherwise the away side is the 'better' side. Note that if (A+3) - B is greater than 10 (or less than -10), the difference is capped at 10.

If the better side wins, then their ranking goes up by (10 - difference) / 10. The losing team loses the same number of points.

If the sides draw, the lesser team ranking goes up by difference divided by 10. The better team loses the same number of points.

If the lesser teams wins, their ranking goes up by (10 + difference) / 10. The better team loses the same number of points.

If one side wins by 15 points or more the ranking changes are multiplied by 1.5.
If the match is at the RWC, the ranking changes are mulitplied by 2.

Therefore, if the All Blacks are at home, and they are more than 7 ranking points clear of their opponent, they cannot gain any ranking points, even by winning by a huge margin. Even beating England (3rd in the IRB ranking, 6.92 points behind) at home wouldn't give them much of a boost.

On the other hand, if we lost to Argentina at home (we're 9.1 points ahead, at home would make it 12.1, capped at 10) we'd drop 2 points and Argentina would gain 2.

[GIGS20]

Nice try sheikh, but this article was obviously written by a New Zealander, because it's bitching about how the All Blacks have been unfairly treated.

Can you re post the points calculation using pictures of fingers and getting rid of references to higher order mathematical concepts such as multiplication?

They might understand it then.