MINNEAPOLIS (AP) - Mike Zimmer has waited a long time to be an NFL head coach, as a 58-year-old who has spent the past 20 seasons in the league as an assistant.

When yet another team picked another candidate instead of him this winter, Zimmer was discouraged enough to consider skipping a second interview with Minnesota and giving up on his goal altogether.

The Vikings were glad he didn't, and so was he.

''I felt like it was a perfect fit. Since the day I've walked in, I don't think it could have been a better situation for me,'' Zimmer said. ''Thank God that I did do that. I think what it does show you, though, is you've got to keep persevering all the time, no matter how despondent you get at certain times.

''When I was thinking about not going on the visit, it had nothing to do with the Vikings. It was just kind of the feeling of a loss until you get over it and then you go about your business.''

Zimmer inherited a lot of talent, from 29-year-old running back Adrian Peterson to the seven first-round picks the Vikings have collected over the past three drafts.

Despite a 1-7 start and a 5-10-1 finish last season that led to the firing of Leslie Frazier, this team is in position for significant improvement if injuries can be minimized and the quarterback position can finally be stabilized.

If not, well, Zimmer's confidence in his defensive scheme, his pattern of persistence, and his trust in offensive coordinator Norv Turner ought to at least keep the Vikings on track until they can return to playoff contention, whether that comes sooner or later.

''I feel pretty good about our chances,'' Peterson said, adding: ''I feel like we have all the pieces.''

Here are some key details to know about the Vikings this season:

KEYS TO THE CASSEL: Tenth-year veteran Matt Cassel was picked over Teddy Bridgewater as the quarterback, with a productive preseason to his credit following a decent performance in relief last year after Christian Ponder faltered. Bridgewater won over the home crowd with a late touchdown drive in an exhibition victory over Arizona, and if Cassel struggles at all the fans will surely be clamoring for the rookie.

''We will hold the quarterback position to the exact same expectations as we do every other position: If you perform, you play,'' Zimmer said. ''If you don't perform then the next guy will get an opportunity at some point.''

PETERSON'S HEALTH: After nearly breaking the single-season rushing record in 2012, Peterson was relatively quiet in 2013 with some nagging injuries and then a sprained right foot that kept him out of two December games. His 2014 goal, then, is simpler: playing a full schedule.

''It's very important to me to make sure that I'm doing the small things, keeping my body healthy and making sure I make it through the entire season,'' Peterson said.

FRIENDLY FRONT FIVE: The Vikings will keep their offensive line the same for the third straight year, with tackles Matt Kalil and Phil Loadholt, guards Charlie Johnson and Brandon Fusco and center John Sullivan carrying continuity and experience as their greatest strength. While their effectiveness regressed at times last season, this is the same group that paved the way for Peterson to rush for 2,097 yards in 2012.

''We're a pretty tight group,'' Kalil said.

SECONDARY, FOR STARTERS: For all the passing problems the Vikings had, the pass coverage was most alarming last year. Opponents threw for 37 touchdowns against them, by far the most in the NFL. The addition of veteran free agent cornerback Captain Munnerlyn was a big boost, and recent first-round draft picks Xavier Rhodes and Harrison Smith are highly regarded starters in the secondary.

But the Vikings reached the end of training camp without clarity about their strong safety and nickel cornerback, with several candidates still in a mix complicated by lingering injuries at both positions. Josh Robinson and Robert Blanton in particular hurt their opportunities by, well, being hurt.

SEPTEMBER TEST: The Vikings will learn a lot about how much improvement has been made to their defense, with a daunting early stretch of games against some of the league's best passers.

Though they caught a slight break with the opener when St. Louis lost Sam Bradford to another season-ending knee injury, but this is what's next: New England, at New Orleans, Atlanta, at Green Bay and Detroit. That means consecutive matchups with Tom Brady, Drew Brees, Matt Ryan, Aaron Rodgers and Matthew Stafford, five of the top seven quarterbacks in the NFL last year in yards passing per game.