How are these numbers calculated?

Big Games

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

Week of 5/2100.0*Chance in playoffs100.0*Average seed
Exeter 29 Harlequins 30 -23.8
-0.2
Bath 19 Northampton 19 -0.4
Week of 5/10100.0*Chance in playoffs100.0*Average seed
Harlequins 19 Bath 16 Out
-0.6
Leicester 31 Saracens 27 -0.2
Games Above .500
Chance Will Make Playoffs