MANKATO, Minn. -- Leslie Frazier dived into history to craft a message for his third training camp as the Minnesota Vikings' coach. Single-season playoff runs, such as the one the Vikings went on last season, are not uncommon. Reaching the postseason regularly over time? That's what Frazier wanted his players and coaches to think about.

Research revealed that only four teams -- the Green Bay Packers, Atlanta Falcons, Baltimore Ravens and New England Patriots -- have made the playoffs in each of the last three seasons. In his opening-night speech to the team, Frazier drove home the challenge of sustaining success in the NFL.

"We looked at teams that have been able to do it over the long haul instead of just hitting it and dropping off," he said. "There are things that have to happen to sustain success. It looks like it's harder to get there than it is to stay there."

The message was especially relevant for the Vikings, who emerged from modest expectations last season to finish 10-6 and clinch a wild-card playoff berth. There is a national perception that they benefited from a perfect storm of factors, and Frazier is keenly aware of that perception. General manager Rick Spielman's decision not to extend Frazier's contract this offseason suggests a level of internal uncertainty as well.

So it's worth nothing that when I asked Frazier to describe the traits of consistent winners, he returned several times to the same theme. Setting up what will be a season-long referendum on his future, Frazier said the most important ingredient is "continuity at the top."

Those teams, Frazier said, "have been constant with their staff. Pretty constant with their front office. I think those things really matter when you're trying to build something that can be sustainable and having some continuity on your staff as well as management. So you're not always trying to reinvent yourself with a new head coach and a new general manager, or turning over in other key places."

THREE HOT ISSUES

The Vikings are hoping that Christian Ponder can continue to build on a strong finish to the 2012 season. Bruce Kluckhohn/USA TODAY Sports

1. Christian Ponder's development: The best way to view Ponder's first full season as the Vikings' quarterback was that he was unacceptably uneven. Based on Total Quarterback Rating, he was a top-10 starter in his first four games, then one of the NFL's worst over the next eight games and, finally, one of the league's best in the Vikings' 4-0 finish.

A reasonable expectation for 2013 is to even out his performance. Put more bluntly: Ponder can't ever be as bad as he was during those eight games of 2012.

In the first few days of training camp, Ponder provided little evidence that he is ready to make that jump to consistency. More than occasionally, his throws went awry on what appeared to be unforced errors. Over three practices, I counted three substantial overthrows of receiver Greg Jennings on mid-range routes. Then there was a go route that took receiver Jerome Simpson four steps out of bounds, along with a ball thrown wildly up for grabs during a blitz drill.

It's fair to point out that Ponder was working in exceptionally windy conditions on the first day, even though no one will want to hear that if it happens in a regular-season game. And I don't want to make it sound as if he didn't make good throws, also. Plenty found their targets. But this post is intended to provide a snapshot of camp when I was there. I'm just telling you what I saw.

2. Young secondary: When training camp opened, the Vikings' nickel defense featured three cornerbacks who have made a combined 22 NFL starts and a grand total of two interceptions. The departure of veteran Antoine Winfield has left a talented but inexperienced last line of defense in a pass-happy division.

The Vikings are hoping that Chris Cook (second-round draft pick, 2010) and Josh Robinson (third round, 2012) can man the top two cornerback jobs. Robinson would slide inside in nickel situations, with rookie Xavier Rhodes (first round, 2013) taking over at left cornerback. None among that trio is an established NFL player, but Frazier shrugged when I inquired about his confidence level. Frankly, there are no other options.

"Whoever is going to be out there," Frazier said, "they're going to be young. We don't have a lot of experience back there. That's one of the things we lost with Antoine: somebody who has seen a lot in our league. The way people throw the ball today, you can't hide bad play in the secondary. So we've got to get those guys up to speed. They are going to be the ones playing for us. It's not like we can go out there and find an All-Pro cornerback or nickel back to come in and help us."

I was especially intrigued by the way Rhodes performed in the early days of camp. He has plenty to learn but is exceptionally strong at the line of scrimmage; he stopped a number of receivers from getting past the five-yard mark in their routes. Rhodes will have to be careful about contact beyond the point, but it has been a while since the Vikings had a cornerback who seems so well-equipped to play press coverage.

3. Adrian Peterson's summer: The NFL's reigning MVP missed two weeks of training camp in 2012. He took limited repetitions when he returned and sat out the preseason while completing recovery from major knee surgery. The exemplary results of that reduced regimen raised an obvious question this summer: Should the Vikings keep Peterson on a strict pitch count once again? Specifically, should he play in the preseason?

Peterson said he would do whatever he is asked but made clear that he wouldn't be insulted if he doesn't see live contact until Week 1 of the regular season. "I really don't care if I do," he said. "I'll go out and do what I do. If not, that's fine as well. It worked out pretty well last year."

Frazier generally takes an old-school approach. At the beginning of camp, at least, he seemed set on getting Peterson some preseason work. "He'll get some work in the preseason," Frazier said. "It won't be like last year where he didn't get any work."

As the preseason gets closer, I wonder whether Frazier's thinking might evolve there. After seeing how Peterson reacted to last summer's regimen, there doesn't seem to be much reason to risk his health in a completely meaningless preseason game.

REASON FOR OPTIMISM

The Vikings traded away Ponder's top receiver (Percy Harvin) this offseason, but overall they have put him in a fair position for success. Minnesota is the only NFC North team to return its offensive line intact, largely because it ponied up on a four-year, $25 million contract to retain right tackle Phil Loadholt. It replaced Harvin with veteran Greg Jennings and rookie Cordarrelle Patterson, pairing them with emerging slot receiver Jarius Wright. Pass-catching tight end John Carlson is getting another chance to team up with Pro Bowler Kyle Rudolph. And oh yeah, the Vikings have the game's best running back and also paid a premium (three years, $7.5 million) to retain one of its best fullbacks, Jerome Felton. Finally, the entire offense is entering its third season in the same scheme. Assuming the general health of that group, Ponder has more than enough around him to succeed.

REASON FOR PESSIMISM

I learned a term recently that I think applies here: Regression to the mean. Suffice it say, a lot went right for the Vikings in 2012. Can we reasonably expect similar micro-results? Is it fair to expect Peterson to approach 2,000 yards again? Can kicker Blair Walsh possibly be as accurate, especially from beyond 50 yards? Will the Vikings have another relatively injury-free season? How many times can they beat Packers quarterback Aaron Rodgers when he throws for 365 yards and four touchdowns, as he did in their Week 17 victory at the Metrodome? Can they be as good in one-score games as they were last year (5-1)? Those factors are why some people aren't sure if the 2012 Vikings were a fluke or if they are poised for sustained success.

OBSERVATION DECK