I have been running an eye over the history books again, looking at the success rates each team has had in Grand Finals (of Finals in earlier years). For the sake of this list, I have not included drawn games, or seasons decided by default (first past post, forfeited finals, drawn finals with premiership awarded to higher team). I have kept Melbourne’s stripped premierships as part of these figures, as they are more about win rates in the game, than actual premierships.
Newcastle 100% (2/2)
Wests Tigers 100% (1/1)
Brisbane 75% (6/8)
Penrith 75% (6/8)
Souths 63% (17/27)
Melbourne 55% (6/11)
St George 55% (15/27)
Canberra 50% (3/6)
Norths 50% (1/2)
St George Illawarra 50% (1/2)
Easts/Sydney Roosters 48% (12/25)
Balmain 47% (7/15)
Canterbury 44% (8/18)
Manly 42% (8/19)
Parramatta 40% (4/10)
Wests 40% (4/10)
North Queensland 33% (1/3)
Newtown 29% (2/7)
Cronulla 25% (1/4)
New Zealand 0% (0/2)
Glebe 0% (0/1)
University 0% (0/1)