Vikings start out No. 23 in ESPN's Football Power Index

ESPN is touting a new power ranking formula for NFL teams called the Football Power Index. We'll get more to what it is in a minute, but I won't bury the most obvious part: the FPI (remember, that stands for Football Power Index and not Federal Ponder Inspector or some such thing) does not like the Vikings. Your purple, in fact, start the season No. 23 out of the 32 NFL teams in that rating.

The Vikings are predicted to have the No. 17 offense, No. 19 defense and No. 20 special teams. But that adds up to a minus-0.8 Football Power Index ranking, which is "the points above or below average a team is expected to be in the coming season," per the site. And minus-0.8 is 23rd in the NFL.

The Packers, on the other hand, have the No. 1 offense, the No. 23 defense and No. 28 special teams but have the No. 1 overall FPI.

How does it work?

Each team's FPI rating is composed of a predicted offensive, defensive and special teams efficiency, as measured by expected points added per play, and that rating is the basis for FPI's game-level and season-level projections.

That's sounds reasonable!

In the preseason, FPI uses a number of predictive factors to project future team strength. The main component of preseason FPI is Vegas expectations.

But relying solely on Vegas has its flaws, and more information is needed to determine what percentage of a team's projected win total can be attributed to its offense, defense and special teams units — the components that make up FPI.

OK, I'm back!

To gather more information on each unit, ESPN polled a panel of NFL experts regarding the expected offensive, defensive and overall performances of teams for the upcoming season. Also added to the model are previous years' efficiencies for each unit, number of returning starters (on offense and defense), coaching/coordinator/quarterback changes and quarterback injuries. After combining all of these factors, a preseason FPI rating is determined for each team, which represents the points above or below average a team is expected to be in the coming season. Preseason FPI will serve as the basis of the early-season predictions but will diminish in effect as the season progresses and we learn more about the actual strength of each team.

So the preseason number is a largely human and/or past-leaning construction that we shouldn't pay too much attention to, particularly in relation to say, a mid-year ranking. That said, it's probably also more relevant than the standard preseason predictions we have seen that indicate the Vikings will do well, which has been happening a lot this preseason.

The most instructive part to me is that if the preseason model is correct, this could be a year where almost every game comes down to five plays one way or the other. That's the way it is for roughly 24 teams every year (four elites, four stinkers, the big squishy NFL middle), but it could be especially true of this year's Vikings.