NFL Nation's Ben Goessling examines the three biggest issues facing the Minnesota Vikings heading into training camp.

Quarterback: This will be the biggest storyline surrounding the Vikings in training camp until head coach Mike Zimmer settles on a starter. Zimmer and offensive coordinator Norv Turner have pledged to hold an open competition during training camp, though the race really figures to boil down to two quarterbacks: veteran Matt Cassel and rookie Teddy Bridgewater, who both got a significantly larger share of snaps during the Vikings' OTAs and minicamp than Christian Ponder. Bridgewater was impressive in his first work with the Vikings this spring, but unless he's clearly the best of the Vikings' quarterbacks in training camp, Cassel figures to start the season as the quarterback. The Vikings re-signed Cassel so they wouldn't have to rush a young quarterback, and in the process, they created a situation in which they can afford to be patient with Bridgewater. If he's the best man for the job, it doesn't seem likely Zimmer will wait to play him. But if he's not fully ready by the end of camp, there's nothing forcing the Vikings to play the rookie.

Remaking the defense: The Vikings committed $20 million in guaranteed money to defensive end Everson Griffen and guaranteed another $16.95 million to secure the services of defensive tackle Linval Joseph and cornerback Captain Munnerlyn. But until training camp, when players put on pads, cornerbacks play press coverage and there's actual contact at the line of scrimmage, it's difficult to assess where the Vikings are in their effort to rebuild a defense that allowed more points than any other unit in the league last season. Rookie linebacker Anthony Barr only had a minicamp with the team as classes at UCLA kept him out of the team's OTAs, but he'll be a prominent figure as the Vikings plan to use the 6-foot-5 linebacker in several different ways. With questions at linebacker (does Jasper Brinkley start in the middle?) and in the secondary (is Josh Robinson good enough to get significant playing time at cornerback?), the Vikings will have plenty to figure out on defense.

New roles for Peterson, Patterson: At age 29, Adrian Peterson is intent on cruising along with his career at a time when most running backs his age start to break down. In Norv Turner, Peterson has a new offensive coordinator who is intent on using him differently. Peterson will be more involved in the Vikings' passing game this season, as Turner and Zimmer seek to convert some of his carries into receptions, giving him more room to work in the open field and making him less likely to take a pounding. Turner also has big plans for second-year receiver Cordarrelle Patterson, whose emergence late last season made many wonder why the Vikings waited so long to make him a big part of the offense. Patterson, who played mostly at split end last season, moved to different spots during the Vikings' offseason program, and Turner seems interested in getting the explosive receiver the ball as much as he can; general manager Rick Spielman said at the NFL scouting combine in February that Turner already had designed about 10 plays for Patterson. If the Vikings can turn him loose in Year 2, he could emerge as one of the NFL's premier playmakers.