This approach has a lot of validility to it. When you compare the Storm and Newtown, both have won 3 premierships. However, the Storm have only existed for 21 seasons, in which there were 14-20 teams competing. Newtown competed for 76 seasons, in which 8-14 teams competed. Melbourne have clearly outperformed most other clubs over their history, while Newtown underperformed.
If we were to assume that each team has an equal likelihood to all other teams of winning a premiership, we can work out how many premierships each team would be expected to have won over its complete history. The ratio of the actual premierships to expected premierships gives how effective each team has been.
The ratings for existing clubs on this basis are:
1. Broncos: 3.04 (6/1.97)
2. Storm: 2.25 (3/1.34)
3. Rabbitohs: 2.06 (21/10.19)
4. Sea Eagles:1.47 (8/5.45)
5. Roosters: 1.35 (14/10.34)
6. Raiders: 1.24 (3/2.42)
7. Bulldogs: 1.12 (8/7.13)
8. Knights: 1.02 (2/1.96)
9. Tigers: 0.82 (1/1.23)
10. Dragons: 0.78 (1/1.29)
11. Eels: 0.71 (4/5.66)
12. Cowboys: 0.65 (1/1.54)
13. Panthers: 0.54 (2/3.67)
14. Sharks: 0.27 (1/3.67)
15. Titans: 0.00 (0/0.75)
16. Warriors: 0.00 (0/1.54)
We can also rate teams against those that no longer exist. These are:
1. St George: 2.01 (15/7.45)
2. Balmain: 1.21 (11/9.11)
3. Magpies: 0.44 (4/9.11)
4. Newtown: 0.37 (3/8.07)
5. Norths: 0.22 (2/9.11)
6. Hunter: 0.00 (0/0.10)
7. Cumberland: 0.00 (0/0.11)
8. Adelaide: 0.00 (0/0.15)
9. Sth Queensland: 0.00 (0/0.18)
10. Perth: 0.00 (0/0.20)
11. Northern Eagles: 0.00 (0/0.21)
12. Newcastle (1908): 0.00 (0/0.24)
13. Gold Coast Seagulls: 0.00 (0/0.67)
14. Illawarra: 0.00 (0/1.12)
15. Annandale: 0.00 (0/1.36)
16. University: 0.00 (0/2.07)
17. Glebe: 0.00 (0/2.60)
Looking at it graphically, you can see the spikes when teams win a premiership. The earlier in the club's history, the higher the spike. Melbourne winning in their second year had a much bigger boost than the Sharks winning in their 50th year.
And zooming in on the last 20 years, we can see that the Roosters have moved in front of the Raiders again.
Over the years, the following clubs have been on top:
1908-1912: Rabbitohs
1913: Roosters
1914-1917: Rabbitohs, Roosters
1918: Rabbitohs
1919: Balmain, Rabbitohs
1920-1925: Balmain
1926: Balmain, Rabbitohs
1927-1965: Rabbitohs
1966-1967: St George
1968-1989: Rabbitohs
1990-1991: Raiders
1992-1998: Broncos
1999: Storm
2000-2018: Broncos