If you take a look at the 2015 Super Rugby table, it's immediately clear that NZ teams have done extremely well. But the overall competition table doesn't show us how teams from one country did against the teams from the other two countries.
I was interested to see what things looked like when we only consider matches that are played between teams from different countries. Factoring out how teams from within a country play each other might give us a clearer picture of the relative strengths of the countries.
I wrote a program to examine this.
The results (see the Details section below) show that NZ group teams won 47/80 (58.75%) of their games overall. But if you look at their record just in out-of-group games, the percentage goes up: they've won 27/40 (67.5%). In contrast, Australian group teams won 34/80 (42.5%) of their games overall, but in out-of-group have won only 14/40 (35%).
I.e., the Australian record is worse than it appears if you just consider their overall competition win/loss percentage. Meanwhile, the NZ teams are doing even better at beating everyone else than it might first appear from their overall record. The South African teams have done exactly as well beating teams from other countries others as they have overall.
This gives us some idea of the overall strength of rugby in the countries: NZ well ahead of RSA, and RSA well ahead of AUS.
However, it doesn't give any indication about whether, for example, New Zealand is likely to beat Australia in a test. That's because the players in the Super Rugby teams that are winning very few games are much less likely to be picked for their national sides.
The program's graphical and textual output following the final round (18) are shown below.
The graph shows how the overall win fraction versus the out-of-group win fraction has changed over time for each of the countries. Only rounds 5 onwards are shown as it took that long to have enough data for the general pattern to stabilize.
Below is the detailed output of the program with results broken down by group.
Results through round 18
Overall vs AUS vs NZ vs RSA
Team P W L D W L D W L D W L D
HUR (NZ) : 16 14 2 0 3 1 0 7 1 0 4 0 0
HIG (NZ) : 16 11 5 0 3 1 0 5 3 0 3 1 0
WAR (AUS): 16 11 5 0 6 2 0 3 1 0 2 2 0
STO (RSA): 16 10 5 1 4 0 0 1 3 0 5 2 1
CHF (NZ) : 16 10 6 0 3 1 0 4 4 0 3 1 0
LIO (RSA): 16 9 6 1 3 1 0 2 2 0 4 3 1
BRU (AUS): 16 9 7 0 5 3 0 1 3 0 3 1 0
CRU (NZ) : 16 9 7 0 2 2 0 4 4 0 3 1 0
BUL (RSA): 16 7 9 0 2 2 0 1 3 0 4 4 0
REB (AUS): 16 7 9 0 3 5 0 3 1 0 1 3 0
SHA (RSA): 16 7 9 0 3 1 0 1 3 0 3 5 0
CHT (RSA): 16 5 11 0 1 3 0 1 3 0 3 5 0
RED (AUS): 16 4 12 0 3 5 0 0 4 0 1 3 0
BLU (NZ) : 16 3 13 0 2 2 0 0 8 0 1 3 0
FOR (AUS): 16 3 13 0 3 5 0 0 4 0 0 4 0
AUS teams:
80 games played (40 vs other groups, 40 within group)
vs NZ W L D
7 13 0
vs RSA W L D
7 13 0
Wins overall: 34/80 (42.50%)
Wins out-of-group: 14/40 (35.00%)
NZ teams:
80 games played (40 vs other groups, 40 within group)
vs AUS W L D
13 7 0
vs RSA W L D
14 6 0
Wins overall: 47/80 (58.75%)
Wins out-of-group: 27/40 (67.50%)
RSA teams:
80 games played (40 vs other groups, 40 within group)
vs AUS W L D
13 7 0
vs NZ W L D
6 14 0
Wins overall: 38/80 (47.50%)
Wins out-of-group: 19/40 (47.50%)
Some notes:
-
The team results table is not ordered by competition points, but by number of wins.
-
RSA teams won 13 out of 20 matches against AUS teams, but only 6 out of 20 against NZ teams.
-
AUS teams have an equal record against NZ and RSA teams: 7 games won out of 20 in both cases.
This repo contains a results file (results.txt) and a Python program to
print stats and make a plot (process.py).
Neither the program nor its input have been fully checked for accuracy yet! I'm fairly certain they're correct.
Usage is as follows:
$ ./process.py --help
usage: process.py [-h] [--rounds ROUND] [--printResults] [--plot]
[--firstPlotRound ROUND]
Print statistics about the 2015 Super Rugby competition.
optional arguments:
-h, --help show this help message and exit
--rounds ROUND Only consider games up to (and including) the given
round. Default is to use data from all rounds.
--printResults Print individual match results (default: False).
--plot Plot a graph showing round-by-round overall and out-
of-group win fractions (default: False).
--firstPlotRound ROUND
The first round of results to show when --plot is used
(default: 5).The results.txt file must have 5 fields per line: round, team1,
points1, team2, and points2. The round numbers must be
non-decreasing so that the end-of-round statistics gathering will work
correctly.