There are a lot of ways to sum up this Vikings’ season-to-date, but one pretty stark way to tell the story is by looking at their week-to-week odds of making the postseason — as defined by Five Thirty Eight. When a team starts with modest expectations, jumps out to a 5-0 record and then loses six of its next seven games to slide all the way back to .500, it’s not hard to spot the trend lines.