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*Average seed
Exeter 29 Harlequins 30 -0.2
Week of 5/10100.0*Average seed
Worcester 28 Gloucester 27 +0.5
Newcastle 13 Exeter 23 +0.1
Games Above .500
Chance Will Make Playoffs