REASONS FOR CONCERN

1. The offensive line played poorly in 2014. The bigger problem is there are no easy answers. Left tackle Matt Kalil was a mess, but the Vikings won't — and shouldn't — give up on a former top-five pick, at least not yet. Phil Loadholt struggled, too, despite being one of the NFL's highest-paid right tackles. And the Vikings need a long-term answer at left guard. The key will be getting the linemen they invested in to play up to their potential.

2. Cordarrelle Patterson took a step backward. The preseason hype for Patterson was enormous after the former first-rounder scored nine touchdowns as a rookie. But Patterson hasn't developed as a route runner and struggled to grasp Norv Turner's offense before being benched. The talent is there, but can he put it all together?

3. Who will be the team's running back? Star back Adrian Peterson was lost for the season after one game because of his legal troubles, leaving the Vikings without an established lead back. His backups, largely Matt Asiata and Jerick McKinnon, did a passable job, but they couldn't make an impact like Peterson, the team's best player.

4. The Vikings struggled to stop the run. While coach Mike Zimmer quickly turned around a vulnerable Vikings pass defense, they allowed their opponents 100 or more rushing yards in 12 of their first 15 games, including four times in five NFC North games to date. As a result, the Vikings rank 25th in rush defense.

5. Needs from last offseason still need to be addressed. The Vikings couldn't get to every need last offseason. They still lack solutions at left guard, strong safety and middle linebacker. Of those positions, middle linebacker — one who can play every down — remains the most glaring need, especially if outside linebacker Chad Greenway does not return. The talent level needs to get better — the Vikings did not have one player named to the Pro Bowl.

MATT VENSEL