In the past six weeks, the Vikings have shed several pieces from the Brad Childress era, made a few sensible-yet-understated free agency moves and injected youth into the 53-man roster.

Will the formula be enough to contend in the stout NFC North?

It depends on whether the Vikings can blend their promising, unproven young players with their aging veterans.

Minnesota’s roster is composed of eight 2011 draft picks, five free-agent signings, three former Vikings practice squad players, one undrafted free agent (linebacker Larry Dean), one United Football League signing (defensive end Adrian Awasom), one waiver claim (former Texans linebacker Xavier Adibi) and 34 returning players from last year’s roster.

More moves could be ahead, but this is what the Vikings have for now.

Hovering around the $120.4 million salary cap for much of the preseason meant less spending for the Vikings, who finally have created some breathing room with a series of moves.

Linebacker Chad Greenway’s five-year, $41 million extension should lessen his cap number after the team franchised him at around $10.1 million in March.

The team released special-teamer Heath Farwell (due $1.75 million) and tight end Jeff Dugan ($775,000) while significantly reducing the salary of wide receiver Greg Camarillo, who was due to make $1.7 million.

As it stands, eight of the Vikings’ 22 starters on offense or defense are age 30 or older. If half of those players produce at a high level, the Vikings will need young, emerging players such as safety Husain Abdullah (fourth year), right tackle Phil Loadholt (third year), wide receiver Percy Harvin (third year) and cornerback Chris Cook (second year) to offset the regression elsewhere.

Without that growth, NFC North foes Green Bay, Detroit and Chicago will be looking to expose the Vikings’ weaknesses twice a year.

These themes will play a part in whether the latest roster concoction succeeds or fails in the coming weeks and beyond:

Spotlight on secondary, wide receiver, O-line: It’s no secret the Vikings have had question marks at these three positions, and the latest 53-man roster reflects as much.

Additions to these spots were made out of necessity. The Vikings needed former Colts left tackle Charlie Johnson only after Bryant McKinnie was labeled unfit to play, and though former Falcons wide receiver Michael Jenkins adds much-needed depth, the No. 2 role still belongs to embattled receiver Bernard Berrian.

Berrian returning to his 2008 form would bring synergy to the Vikings’ passing attack.

The secondary, meanwhile, did little for insurance in case the knees of corners Cedric Griffin and Cook don’t hold up or the two-headed strong safety combination of Jamarca Sanford and Tyrell Johnson fizzles out.

Two big concerns for the Vikings are depth on the offensive line and playmaking ability in the secondary, according to an AFC scout who spoke on condition of anonymity.

The top three backups on the line – center/guard Jon Cooper, former practice squad tackle Patrick Brown and former practice squad guard Seth Olsen – have a combined one NFL start.

“You look at the secondary, and although Winfield’s really solid, there’s really not a true playmaker there,” the AFC scout said. There is “nobody who is going to make a play to change momentum or excite you. I think the offensive line, even without a lot of star power, can get by with what they have, but if someone goes down, that depth is an issue.”

Johnson, drafted in the second round in 2008, is a fluid athlete but too often makes the “almost” play by taking a bad angle or not anticipating, the AFC scout said.

Will youth emerge? The Vikings have spent recent years collecting defensive line talent in the later rounds of the draft – tackle/end Christian Ballard (fourth round, 2011), end Everson Griffen (fourth round, 2010) and tackle Letroy Guion (fifth round, 2008).

All three players have obvious potential but will be asked to shoulder a bigger load with Kevin Williams serving a two-game suspension for the StarCaps case.

Guion likely will get the most chances, but Ballard and Griffen will get their share of snaps.

“I can’t fill Kevin’s shoes, but I can play to the best of my ability at my position,” Guion said.

Erin Henderson finally gets his chance at weak-side linebacker, and because the Vikings didn’t make a splash to replace Ben Leber, Henderson must be as disciplined as he is athletic.

The Vikings need Cook more than ever as the outside corner in the nickel.

Rewarding the contract: Two names come to mind here: defensive end Brian Robison (three years, $14.1 million) and quarterback Donovan McNabb (one year, $5.05 million).

McNabb says he’s motivated by his second chance after the Washington debacle and is grateful his old friend, coach Leslie Frazier, supported him through the trade.

Because the Vikings know what to expect with running back Adrian Peterson and receiving options such as Harvin and Visanthe Shiancoe, McNabb must return to his Philadelphia form for the Vikings to have a chance.

Robison was a scrappy pass-rushing backup whose play persuaded the Vikings to part with Ray Edwards. His presence against the run and off the edge will be crucial for 2011 success.

“He’s an interesting player to watch because he was a guy you liked in a limited role, but can he consistently penetrate and stop the run?” the AFC scout said.