Seattle Seahawks Playoff Chances 2013 50/50

Beat St. Louis 27-9, average seed up 1 to 1
13-3-0   .813

How are these numbers calculated?

Big Games

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

Week of 12/12100.0*Average seed
NY Giants 0 Seattle 23 +0.4
Tampa Bay 14 San Francisco 33 -0.3
Week of 12/22100.0*Average seed
San Francisco 34 Atlanta 24 -0.5
Seattle 10 Arizona 17 -0.2
Week of 12/29100.0*Average seed
Seattle 27 St. Louis 9 +1.0
Arizona 20 San Francisco 23 -1.0
Games Above .500
Chance Will Make Playoffs