How are these numbers calculated?

Big Games

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

Week of 4/8100.0*Premier Division Playoff100.0*Average seed
Evesham United 1 Mangotsfield 0 -3.9
+0.1
Swindon 2 Tiverton Town 2 -3.0
-0.1
Yate Town 3 North Leigh 2 +0.3
+0.1
Salisbury 7 Wantage Town 0 -0.2
North Leigh 2 Yate Town 1 -0.2
Week of 4/15100.0*Premier Division Playoff100.0*Average seed
Shortwood United 1 Swindon 0 No
-0.4
Bideford 1 Evesham United 1 -0.1
North Leigh 1 Paulton Rovers 0 -0.2
Mangotsfield 1 Salisbury 3 +0.2
Swindon 5 Wantage Town 0 +0.5
Didcot Town 1 North Leigh 1 +0.1
Bishop's Cleeve 2 Mangotsfield 2 +0.0
Week of 4/22100.0*Premier Division Playoff100.0*Average seed
Larkhall Athletic 3 Swindon 1 -0.5
North Leigh 1 Taunton Town 0 -0.3
Mangotsfield 2 Didcot Town 3 +0.1
Points
Chance Will Win Championship