How are these numbers calculated?

Big Games

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

Week of 8/11100.0*Chance in playoffs100.0*Home Advantage100.0*Average seed
West Auckland 3 Southern 5 In
+17.5
+0.2
South Auckland 4 Southern 0 -49.7
-0.5
South Auckland 6 West Auckland 0 No
-0.3
Points
Chance Will Make Playoffs