How are these numbers calculated?

Big Games

How we did last week and who we should root for this week.   Explain

Week of 7/30100.0*Chance in playoffs100.0*Average seed
Southern 2 Botany 3 +21.0
+0.5
Dunedin 4 Canterbury 7 -3.8
-0.1
Dunedin 5 Canterbury 7 -2.6
-0.1
Week of 8/6100.0*Chance in playoffs100.0*Average seed
Canterbury 13 Botany 4 Out
-0.5
West Auckland 6 Southern 3 -11.3
-0.3
Week of 8/13None
Points
Chance Will Make Playoffs