The Vikings have made a lot of moves this offseason relating to their woeful offensive line. What's become apparent, though — even after the signing of Alex Boone to a significant contract and the decisions to bring back/retain Mike Harris, Phil Loadholt, Matt Kalil and Carter Bykowski — is that the Vikings' most significant offseason move on the offensive line might not involve a player.

Rather, it was the hiring of Tony Sparano to replace Jeff Davidson as offensive line coach.

The moves they have made personnel-wise — at least for now, pending the signing of a significant free agent tackle such as Andre Smith, who visited Sunday, or the use of a high draft pick on a player expected to start right away — do not have the feel of an overhaul. Rather, they have the distinct feel of creating competition and depth with mostly known commodities, many of whom will be in the final year of their contracts in 2016.

The competition factor and the short-term nature of many of those deals strike me as approaches designed to see how much Sparano can improve a unit that allowed the most pressure on Teddy Bridgewater of any quarterback in the league last year (per Pro Football Focus).

If it works, and Sparano can upgrade the line from a weakness into a strength, the Vikings can attempt to retain the pieces they want going forward while also knowing that a plug-and-play approach might work as long as Sparano is here. If the line falters, the likes of Loadholt, Harris, Kalil, Joe Berger, Zac Kerin and Jeremiah Sirles — all of whom are in the final years of deals in 2016 — can be easily dispatched while a true overhaul takes place in 2017.

The risk in this, of course, is obvious: The Vikings are loaded up to be competitive in 2016 at virtually every other position — good enough, in the eyes of the organization, to make a legitimate run at the Super Bowl.

The Vikings brought in former head coach Tony Sparano to whip their offensive line in shape. But do they need more talent than what’s on the roster now?

But Adrian Peterson turns 31 next week. And Bridgewater needs to take a step forward in 2016. This might be the one season when both of those key offensive players are somewhere near peak performance at the same time. And the Vikings, unless there are more moves still coming, are taking a chance on that line's production in 2016 — production that will be critical to the success of Peterson and particularly Bridgewater.

Remember, even when Loadholt and John Sullivan were healthy in 2014, the line graded out as No. 21 in the league per PFF. Simply signing Boone, potentially getting guys back healthy and having more depth made primarily of holdovers offers far less than a guarantee that the line will be greatly improved in 2016.

That's why I'd love to see at least one more significant addition (and maybe even two: one each from free agency and the first two days of the draft) before the dust settles. If not, the Vikings will be putting an awful lot on Sparano's shoulders.

That's not to say he isn't up to the challenge. It is to say it's still a risk.