The Vikings have added Kirk Cousins, Sheldon Richardson, Mike Hughes and George Iloka to a team that won 14 games last season. General Manager Rick Spielman had a good offseason, but the most important personnel decision for the Vikings might have been made by Joe Berger.

Berger started 46 games at center or guard for the Vikings over the past three years. During a 12-year NFL career, he started 16 games in a season twice. The Vikings made the playoffs each time.

Berger decided to retire after last season. Had he returned, he likely would have begun training camp as the starting left guard. Instead, Nick Easton was given a chance to win the job, and was lost for the season three weeks ago because of a neck injury.

Sunday, Vikings coach Mike Zimmer announced in the morning that starting center Pat Elflein would not practice this week but said that Elflein wouldn’t necessarily start the season on the physically-unable-to-perform list. Maybe Elflein starts the season at center and is rusty. Maybe he is eased into action. Or maybe he does wind up on the PUP list.

Tom Baker for Star Tribune
VideoVideo (02:53): After the narrow win over Seattle, Vikings head coach Mike Zimmer feels the team still has much room for improvement.

What’s certain is that Berger, had he been motivated to play, would have solved a major problem for the Vikings had he returned.

At the very least, he might have saved the Vikings a seventh-round draft pick.

Sunday afternoon, after they left the practice field, news broke that the Vikings had traded a seventh-rounder to the New York Giants for Brett Jones, who played 12 games at center last year.

Whether the trade should cause or assuage worry about the offensive line remains to be seen. What we know is that the Vikings have to find a way to field a functional line, or a remarkably talented roster will be wasted.

Before the Vikings signed Cousins, the best pure passer they had employed this decade was Sam Bradford. Combine arm talent, composure, intelligence and accuracy, and Bradford is an easy choice.

If he could stay healthy, he might prove to be a better passer than Cousins himself. Of course, if he had stayed healthy, the Vikings may never have pursued Cousins.

Bradford did not make the playoffs as a Vikings starter. In this decade, the quarterbacks who have taken Vikings teams to the playoffs are Christian Ponder, Teddy Bridgewater and Case Keenum. In 2008, they made the playoffs with a combination of Tarvaris Jackson and Gus Frerotte playing the position.

Ponder was not a quality NFL quarterback. Bridgewater made the postseason before he had matured, or mastered the deep pass. Keenum took over for an injured Bradford and excelled for an outstanding team, but did not perform well enough in the playoffs for the Vikings to keep him instead of investing heavily in Cousins. Jackson was a backup miscast as a starter, as was Frerotte.

This is an elaborate way of saying that as much as we obsess over quarterbacks, they are often at the mercy of those around them. Nick Foles beating Tom Brady in the Super Bowl is the ultimate example of this.

A strong line helped a mediocre Vikings team to the playoffs, and Adrian Peterson to a 2,000-yard season against defenses intent on stopping him.

A strong line helped Bridgewater and Peterson to the playoffs in 2015.

A line decimated by injuries kept the Vikings from making the playoffs in 2016.

A solid if unspectacular line helped the Vikings to 14 victories last year.

Jones does not have the résumé of a savior. He lost a competition with Jon Halapio to be the Giants’ starting center this season. Last year, the Giants offensive line appeared to be a weakness as the team finished 21st in offensive yards and 26th in rushing yards.

If Jones was acquired to provide depth behind Elflein, the Vikings line should be good enough to support a playoff team.

If Jones is forced to start frequently, Berger’s retirement may trump Cousins’ signing as the most pivotal decision of the Vikings’ dramatic offseason.