Minnesota Vikings offensive line
Minnesota Vikings offensive line — USA Today Sports

Largely lost in the shuffle of their 13-win campaign and appearance in the NFC title game are the strides the Vikings' O-line made last season.

Rick Spielman spent a pretty penny to rectify the NFL's worst OT situation one year earlier in signing Riley Reiff and Mike Remmers to stabilize the flanks. Minnesota also coaxed impressive mileage from third-round C Pat Elflein, who was relatively solid in 16 starts prior to suffering an ankle injury in the conference championship that required surgery and him beginning camp on the PUP list.

Reiff is back at left tackle, and Remmers could return to right tackle or right guard, depending on the growth of talented second-round Penn State product Brian O'Neill. But on Thursday came news that starting LG Nick Easton, a player whom Minnesota is high on, as evidenced by the second-round tender it placed this offseason on the restricted free agent, has a herniated disc requiring surgery that will end his fourth season before it begins.

The rest of Minnesota's interior O-line also is in a precarious state, with Elflein still on the PUP list and a battle underway to replace retired RG Joe Berger, who quietly was the rock of the unit, starting 46-of-48 possible games since 2015.

And we've yet to mention easily the toughest part of the offensive line in flux — Minnesota only now beginning to turn the page from the tragic, sudden passing on July 22 of O-line coach Tony Sparano.

A rival NFC executive told PFW earlier this week that Minnesota would miss Sparano more than offensive coordinator Pat Shurmur or any other offseason defection — and it makes sense. Sparano was masterful in getting a brand-new front five up to speed last season, his second with the club, when his unit helped the Vikings improve from last in the NFL in rushing and 28th in offense to No. 7 and No. 11, respectively, despite losing Sam Bradford after Week 1 and Dalvin Cook's ACL injury abruptly halting his spectacular rookie start in October.

Minnesota named Clancy Barone and Andy Janocko as co-offensive line coaches to replace Sparano this season. With all due respect to them, the drop-off in experience is vast as the Vikings again seek stability with plenty of moving parts. Those contingencies are also short on experience. Tom Compton was a nice offseason signing and is ideally suited as a swing blocker, but Danny Isidora and Cornelius Edison — who were in Minnesota's makeshift starting line as recently as Thursday's camp practice — have one NFL start between them, courtesy of Isidora as a fifth-round rookie last year.

Of course, the most important part of Minnesota's Super Bowl puzzle, it believes, was obtained in March with the signing of Kirk Cousins to the first fully guaranteed multi-year QB contract in NFL history. Part of the Vikings' sales pitch, in addition to the unprecedented contract and outstanding skill talent, was a line whose arrow appeared to be pointing up until recently.

And last year proved that Cousins needs his line firing on all cylinders to maximize his performance. Although he threw for 4,000-plus yards for a third consecutive season, Cousins' sack percentage was a career-high 7.1, while his passer rating (93.9), INT percentage (2.4) and yards per attempt (7.6) were all his lowest as the starter in Washington.

Digging a little deeper, we find that Cousins' 2017 struggles crescendoed around midseason, absorbing 27 of those sacks between Weeks 6-12, when Trent Williams, Brandon Scherff and Shaun Lauvao were in and out of the lineup. Say what you will about Case Keenum's chances of replicating his improbable 2017 campaign — clearly Minnesota decided it would rather bank on Cousins' consistency — but Keenum is more fleet-footed and his best quality last season was his pocket presence. Cousins? His 342 yards surrendered on sacks led the NFL by a decent margin.

Are the Vikings suddenly doomed in 2018? That's a bit of a stretch. They're still absolutely loaded on defense and at the skill positions, and still have plenty of promise in the coaching ranks with a pair of assistants who could become head coaches, George Edwards and John DeFilippo, under highly regarded Mike Zimmer.

But an early obstacle has not only emerged in the way of Minnesota's Super Bowl path — it's getting larger rather quickly.