Shutdown Countdown: Vikings improving, will it be too late for Adrian Peterson?

Shutdown Corner is previewing all 32 teams as we get ready for the NFL season, counting down the teams one per day in reverse order or our initial 2014 power rankings. No. 1 will be revealed on Aug. 2, the day before the preseason begins with the Hall of Fame Game in Canton.

It's almost too easy to start wondering if Adrian Peterson is going to be stuck with an Ernie Banks-type career without any real postseason success.

Peterson has played seven seasons, won an MVP award, rushed for 10,115 yards, already is a lock for the Pro Football Hall of Fame, and he has appeared in only four playoff games. He has been a winner in just one of those games, a 34-3 win over Dallas before losing a heartbreaking NFC championship game at New Orleans the next week.

Peterson is only 29, so he still has time to experience some real postseason success (maybe have a Walter Payton-type career), but one of the all-time greats will likely be stuck in a familiar spot this season, as the bright spot on an otherwise dreary team.

The Bears and Cowboys got a lot of attention for their bad defenses, but Minnesota's might have been the worst in the NFL last season. The Vikings were 31st in yards allowed and dead last in points allowed, giving up exactly 30 per game. Offensively, Minnesota was one of just seven teams with more interceptions than touchdowns. Head coach Leslie Frazier was fired. Mike Zimmer, an intense defensive coordinator, was hired. He'll help fix the defense, but they can have a huge improvement and still be below average. The offense still needs some work, too. 

While brighter days may be ahead, it would be a pretty big upset if we see the great Adrian Peterson back in the playoffs this year.

2013 review in less than 25 words: The Vikings started 1-7, and even a 4-3-1 finish that included a win over Philadelphia couldn't save Leslie Frazier's job.

Is the roster better, worse or about the same?: The Vikings added a bunch of new faces, and it will probably result in a better roster. The Vikings pretty clearly had a plan to sign younger talent in free agency who would still be productive by the time the team turns things around. None of Minnesota's signees have been in the NFL more than five seasons. Other longtime veterans, like defensive linemen Jared Allen and Kevin Williams, weren't brought back. There was a long-tern plan in place, and not just a bunch of quick fixes from a front office with no job security. It was a pretty smart offseason in Minnesota. 

Best offseason acquisition: Linval Joseph was one of the acquisitions that summed up Minnesota's plan. The big defensive tackle from the Giants had a productive four seasons as a starter in New York, and doesn't turn 26 until October. Was he overpaid at $31.5 million over five years? Perhaps, but it makes more sense for a rebuilding team to pay a premium for good, young players than get old veterans who won't be productive by the time things turn around for the franchise.

Achilles heel: The Vikings' pass defense was a mess last season, allowing 4,595 yards and a 98.6 quarterback rating. It doesn't help that Minnesota has to battle the passing offenses of Green Bay, Chicago and Detroit each twice a year. The Vikings are trying to improve the secondary. Cornerbacks Captain Munnerlyn (Carolina) and Derek Cox (San Diego) were signed. Cornerback Xavier Rhodes, a 2013 first-round pick, could be a future standout. Harrison Smith is a terrific safety, and one of Minnesota's problems last year was that he missed eight games with injury. The Vikings' secondary will be better, but the pass defense is a big reason Minnesota won't be a contender in the NFC North.

Position in flux: The Vikings committed a big mistake in the 2011 draft, reaching for Christian Ponder with the 12th overall pick just because he was the top quarterback on the board and they needed a quarterback. As we've seen, Ponder is not an NFL starter. Neither is Matt Cassel, really. That's why the team moved up and snagged Teddy Bridgewater with the last pick of the first round this year.

Bridgewater's draft stock fell, but he spent most of 2013 considered a top quarterback prospect and had a good season at Louisville. It wouldn't be a surprise if he has a very good career.

His addition means a rare three-way quarterback battle to start training camp (although, it would be a surprise if Ponder won the job).

Bridgewater is Minnesota's quarterback of the future, but we'll see in August if the coaching staff is comfortable starting him from Week 1 on.

Ready to break out: Receiver Cordarrelle Patterson is the obvious choice, and if you've read anything this offseason you know he's a popular breakout pick in his second season. So we'll go with another player who should have a breakout season in Minnesota: Defensive end Everson Griffen.

Griffen was set to be an attractive free agent, and the Vikings realized that and gave him a five-year, $42.5 million deal to keep him off the market. That's a ton of money for a guy with one NFL start over his first four years and 17.5 sacks in 59 games. But the Vikings are betting on talent, and Griffen has a lot of it. That deal might turn out to look horrible if Griffen can't embrace a bigger role. There's a better chance that the Vikings knew what they were doing locking up their young pass rusher.

Stat fact: Peterson has never had a season with more than 43 catches, and averages less than 30 per season. That should change this year. New offensive coordinator Norv Turner has long used his tailbacks as receivers out of the backfield, and sounds committed to getting Peterson the ball in space in the passing game. That makes sense for many reasons, and should help limit some of the wear and tear off Peterson's body.

Schedule degree of difficulty: The Vikings play in a tough division, which doesn't help. What will be watched closely is if the Vikings have a home-field advantage playing at the University of Minnesota while their new dome is built. Four of their last six games are at home, so get ready for some brutally cold games.

Burning question

This team’s best-case scenario for the 2014 season: The NFC seems too tough for the Vikings to be a legitimate playoff contender. But Zimmer and some additions could significantly improve the defense. Peterson carried the team to an unlikely playoff berth in 2012, and it's hard to count him out. But he'll need some help. Maybe the Vikings can find some stable quarterback play among their three contenders for the job.

And here’s the nightmare scenario: It would be a shame if the Vikings don't figure things out until Peterson is past his prime. LaDainian Tomlinson, for one example, started wearing down significantly in his age 29 season, after 2,365 carries. Peterson is 29 with 2,033 carries. There have been only 46 1,000-yard rushing seasons by players who are at least 30 years old. So you never know when he'll slow down. It will be a rough time for the franchise when Peterson starts to look human (although, Payton was fine at 34 and John Riggins was strong at 35, so who knows how long Peterson can keep it going). Even if Peterson is still good as ever this year and for many more, it'll be a little scary if some of the Vikings' signees don't play well and Bridgewater doesn't show he can be the answer at quarterback. The Vikings need some reinforcement that they're on the right path.

The crystal ball says: The Vikings aren't good enough to be a contender, and won't be. But some of the team's recent picks and signings, especially Bridgewater, should perform well this season and provide some optimism. Even if everything comes together well, the Vikings still seem at least a year or two away. Will Peterson still be the game's best running back when they get there?

Previous previews:
32. Jacksonville Jaguars
31. Oakland Raiders
30. Washington Redskins
29. Cleveland Browns

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Frank Schwab is the editor of Shutdown Corner on Yahoo Sports. Have a tip? Email him at shutdowncorner@yahoo.com or follow him on Twitter! Follow @YahooSchwab