The Vikings would never think of placing Adrian Peterson on the field during a preseason game. They don't want one of their most important players to get hurt during a meaningless exhibition.
This might be a good time for agents of the other Vikings starters to ask this question on their behalves:
What are we, Spam?
Saturday, the Vikings will again pretend, like the rest of the NFL teams, there is value in preseason games. They will play their starters for a limited number of plays, then pull them off the field to keep them safe.
Let's call it American Roulette. It's OK to risk injury for 15 snaps, just not for 60. It's as illogical as a seat license, and it exists for the same reason.
Last Saturday, the Vikings lost right tackle Phil Loadholt for the season because they used him in a preseason game. This Saturday, the Vikings will risk the rest of their starters, other than Peterson, in a preseason game.
Coaches and NFL traditionalists will defend the value of preseason games because that's what coaches and NFL traditionalists do. They will speak to the value of game action in sharpening veterans and testing rookies and fringe players.
But that's not the reason preseason games exist. They exist because they make money.