Back to work for the Vikings means back to Mankato, Minn., their preseason home away from home for almost five decades.

For the 49th consecutive year, the Vikings will assemble for training camp Thursday at Minnesota State Mankato. Only the Green Bay Packers have trained longer in one location; they’ve been at St. Norbert College in De Pere, Wis., since 1958.

Encamping no longer is en vogue around the NFL. Eighteen of 32 teams will train at their regular-season facilities compared with just five in 2000.

Minnesota’s initial walk-through is Friday morning, the first of 14 two-a-day workouts before camp breaks Aug. 14. There will be 13 full-pad practices.

The preseason opener is Aug. 8 against the Oakland Raiders at TCF Bank Stadium.

Here are three story lines to watch:

WILL TEDDY STORM THE CASSEL?

Ten-year veteran Matt Cassel received most of the reps during offseason workouts and is the presumptive starting quarterback, but rookie Teddy Bridgewater saw plenty of first-team action.

Coach Mike Zimmer was adamant the No. 1 quarterback job is open for the taking, even for the banished Christian Ponder.

The Vikings would love for Bridgewater to seize his opportunity; however, they are not demanding that the 32nd overall pick in the 2014 NFL draft lead them back to the playoffs. Cassel has proved enough as a backup, spot starter and full-blown No. 1 to keep Minnesota relevant while the team develops Bridgewater.

SHORING UP THE ‘D’

In 2013, no team allowed more points per game (30) than the Vikings, who also ranked near the bottom in yards allowed (398) and penalty yards (1,003 total).

The defense was a hot mess of mismatches and dysfunction under defensive coordinator Alan Williams, who was openly criticized by his own players.

New coordinator George Edwards is expected to deploy a more disciplined and aggressive unit that is banking on defensive ends Brian Robison and Everson Griffen to anchor a front four that lost veterans Jared Allen and Kevin Williams.

The linebacker corps features stiff competition among incumbents Chad Greenway, Audie Cole, Gerald Hodges, Michael Mauti and returner Jasper Brinkley, who spent last season in Phoenix. And don’t overlook athletic rookie Anthony Barr.

NEW SHERIFF IN TOWN

Zimmer brings an intensity and hands-on coaching style evident in the profanity and blunt interactions he had with players during spring minicamps.

After working through several years of rejection before finally landing a head coaching job, Zimmer proved he has patience, and he is not going to let unpreparedness or inattention waste this opportunity, regardless of whether he gets a mulligan with a Vikings team that went 5-10-1 last season.

His biggest decision will be naming a No. 1 quarterback, which Zimmer said he will do sooner rather than later in the preseason to allow his guy to settle into the role.

Certainty at the position is critical after the three-ring circus Minnesota endured at quarterback in 2013.

Follow Brian Murphy at twitter.com/murphPPress.