January 8, 2011

What Wins Premierships? A Statistical Analysis

Put simply, defence.

Certainly, the flashy halfback or the representative centre will assist any team on the path to premiership glory. A team that can blow the other one off the park on any given weekend will occupy the spotlight.

However, a team that isn't endowed with attacking gifts can overcome these with great defence. The Dragons proved this to great effect last year by conceding an average of just 12.46 points all season. That's barely more than two converted tries!

By contrast, the Dragons scored only 90 tries all season. That's 14 less than South Sydney, who won six less games than St George Illawarra and still missed the finals.

Let's see how the 2010 Dragons stack up against other defences in the NRL era:

11.45 - 2008 Storm*
11.54 - 2007 Storm**
12.25 - 1999 Eels
12.46 - 2010 Dragons**
12.92 - 1998 Broncos**
13.71 - 2009 Dragons
13.83 - 1999 Sharks
14.50 - 2009 Storm**
14.54 - 1998 Eels
14.79 - 2008 Sea Eagles**

** Denotes that team won the grand final in that season
* Denotes that team lost the grand final in that season

Looking at this table, one can deduce that the past four premiership-winning teams all had cracking good defence - ironically though, the best defensive unit since the NRL started lost the grand final 40-0 in that same season.

One also has to question how the 1999 Sharks and 1999 Eels both feature in this list yet neither played in the grand final of that year.

Let's now go back to 1982 (the start of the expansion era and Winfield Cup) to see which teams were the leading defensive units of that time, and how they subsequently performed.

1982 - Parramatta Eels - 10.92 - Premiers
1983 - Parramatta Eels - 11.27 - Premiers
1984 - Canterbury Bulldogs - 9.88 - Premiers
1985 - St George Dragons - 11.00 - Lost Grand Final
1986 - Canterbury Bulldogs - 11.00 - Lost Grand Final
1987 - Canterbury Bulldogs - 13.17 - Missed finals
1988 - Penrith Panthers - 11.73 - Lost Minor Semi Final against Balmain
1989 - South Sydney Rabbitohs - 9.41 - Lost Preliminary Final against Canberra
1990 - Canberra Raiders - 11.14 - Premiers
1991 - Penrith Panthers - 11.36 - Premiers
1992 - Illawarra Steelers - 11.77 - Lost Preliminary Final against St George
1993 - Manly Sea Eagles - 10.55 - Lost Minor Semi Final against Brisbane
1994 - North Sydney Bears - 13.23 - Lost Preliminary Final against Canberra
1995 - Manly Sea Eagles - 11.27 - Lost Grand Final against Canterbury
1996 - Manly Sea Eeagles - 8.68 - Premiers
1997 (ARL) - Newcastle Knights - 14.55 - Premiers
1997 (SL) - Cronulla Sharks - 12.78 - Lost Grand Final against Brisbane
1998 - Brisbane Broncos - 12.92 - Premiers
1999 - Parramatta Eels - 12.25 - Lost Preliminary Final against Melbourne
2000 - Brisbane Broncos - 14.92 - Premiers
2001 - Parramatta Eels - 15.62 - Lost Grand Final against Newcastle
2002 - Sydney Roosters - 16.88 - Premiers
2003 - Canterbury Bulldogs - 17.46 - Lost Preliminary Final against Roosters
2004 - Canterbury Bulldogs - 15.33 - Premiers
2005 - Parramatta Eels - 19.00 - Lost Preliminary Final against North Queensland
2006 - Brisbane Broncos - 16.33 - Premiers
2007 - Melbourne Storm - 11.54 - Premiers
2008 - Melbourne Storm - 11.45 - Lost Grand Final against Manly
2009 - St George Illawarra Dragons - 13.71 - Lost Semi Final against Brisbane
2010 - St George Illawarra Dragons - 12.46 - Premiers

Note that due to tries being worth three points in 1982, I adjusted Parramatta's actual average from that year (9.31) by adding one point for each of the 42 tries they conceded so that their tally would be consistent with the others in the list.

So of the 30 premierships decided in 29 seasons since 1982, 14 of them have been won by the team with the most outstanding defence at the conclusion of the regular season. A further six teams lost the grand final that year. 20 of the 30 grand finals featured the team with the best defence that season - that's rather good betting odds if you ask me.

Of the ten remaining teams that failed to make the grand final, many notable "chokes" are featured, such as the 2009 Dragons, 2005 Eels and 1999 Eels. Only the 1987 Bulldogs failed to make the finals at all, although their defensive tally that year stands up very well against those registered by teams from the past decade.

Of the three teams that conceded less than ten points per game, two went on to premiership glory - the 1984 Bulldogs and 1996 Sea Eagles - ironically, both clubs were celebrating their 50th anniversary in those seasons. Only the 1989 Rabbitohs failed to win a premiership and concede less than ten points a game - although I'm sure it has been done on numerous occasions before 1982, although that is the rugby league equivalent of ancient history).

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