What is the correct way to calculate implied odds for a group of teams on a futures bet? I calculated the implied odds from 5Dimes on all teams to win the AFC by converting to decimal odds and dividing by this # summed across all teams. I found that this new no-vig # implied that there was value on the field for some teams.

For example, I calculated KC at 21.2% with vig (+370), and 16% without vig. The 16% translates to +525 as the fair line. The field against KC to win the AFC is -465. This would imply the field bet has value. This occurs with the favorites only. Thus I think my methodology of dividing the vig odds (+370 or 21.2% for KC) for all teams the same # to get the implied odds is wrong. Thoughts?