I do think the Vikings would be best served by accepting the reality of the modern NFL. This is a passing league. Like many, I'm tired of the excessive use of FBs and TEs. I think the base set should be Jennings, Patterson, Simpson or Wright, Rudolph and AP in the backfield. Open it up and create some space. Force other teams to use more CBs, which may ironically open up more holes in the ground game. Peterson is perceived as a power-runner, but he seems to be way more effective in space.
I think scheme is part of the problem on defense too. Especially with the decline of JA and KWill, there's not enough pressure with the front four. I would like to see more blitzes. They're going to get carved up over the middle either way. Their best chance of getting off the field is to sack the QB or force a turn-over. If they give up a big play every now and then, so be it. At least that'll address the fatigue excuse.
Interestingly they had Killer Lewis ( Ray to some of you) on after MNF last night and asked him about stopping Peyton Manning and he said that last year before the playoffs he went to the coaches and told them they needed to run a zone defense against the broncos to win and that after watching the playoff games he has played in if teams went with man on man coverage he won every game and the only times he was beaten was when teams went with a zone defense and used a ball control offense.