The issue of how to rank players in Australia is oft debated. The major problem is that a ranking system involves ranking individual players when they mostly play in teams of two or three. Additionally tournaments around the country vary widely in skills level present. The PFA has a system that gives players points for performance in a series of major competitions across the country.
Another often referred to system is the one developed by Peter Wells of MyPetanque fame! He has teamed up with Rodney Deakin of Victoria to take a look at three different systems in a very interesting paper called Petanque Ratings. Warning! There's some maths contained in this paper!
There's a saying around the sport that you can use any Ranking system you like but the top 20 players will appear in every one of them. The question in making selections for a team is based on more than rankings - availability, willingness to meet costs associated, compatibility with others, specific skills, etc. The PFA Selection Policy looks at these issues and details how the PFA Selection Panel makes its decisions.