John Sullivan had been missing from Vikings practice for three weeks with a back injury — and it wasn't the standing on the sidelines or visible an on exercise bike type of missing. He was flat-out gone, and the updates from the Vikings were just as vague even as coaches tried to downplay his absence.

It's really not terribly surprising, then, that we learned Thursday that Sullivan is going on injured reserve/designated to return, which will keep him out for roughly half the season and realistically could keep him out for more while he recovers from a lumbar microdiscectomy procedure he underwent on Wednesday.

The lack of surprise, however, doesn't make the news any less troubling for the Vikings or their fans. The Vikings had already lost right tackle Phil Loadholt for the season. There were question marks up and down the line — except at center, where the steady Sullivan had been a rock in terms of both durability and performance.

Veteran Joe Berger should be at least an adequate fill-in for number 65, but shifting him into full time duty at center negates his versatility and leaves the Vikings even more dependent on a lot of unknowns to open holes for Adrian Peterson and block for their franchise quarterback, Teddy Bridgewater.

If the line is unable to hold up, the Vikings offense could very much resemble a shiny car with plenty of gadgets and a bad engine.

If that wasn't enough, I stumbled upon the FiveThirtyEight NFC North preview. It's about a week old by now, but I had missed it in the midst of the tidal wave of NFL content that comes out this time of year.

Unlike many of the flattering prognostications that have come the Vikings' way this year, this one wasn't so keen.

FiveThirtyEight puts the Vikings' expected win total at 7.5 and their playoff odds at 24.3 percent. Basically, everyone in the division is projected to finish with fewer than 8 wins except the Packers.

The preview notes that many expect the Vikings to make a leap because they're a young team that figures to keep improving, but it also douses some water on that notion with historical figures that show young teams similar to the Vikings improve on average by about one win from year to year, not the two or three it would likely take for Minnesota to reach the playoffs.

The good news is that the games are played on the field, not on paper. But that brings us back to the bad news of Sullivan.

With the NFL slated to kick off tonight and the Vikings' opener four days away, there are still plenty of reason to be optimistic about the Vikings. I'm on record with a 10-6 prediction, and I'll stick with it — while also acknowledging that I could end up way off-base.