Actually, Moving up to draft players is a good move if the players end up as good as the scouts think they are. The Packers moved up for Clay Matthews, and that was a pretty good move for them. Harrison Smith looks like a good move for the Vikings so far.
On the other hand, the Vikings sometimes move up to select players that would have been there later. I doubt they had to make the moves they did for Ponder, Jackson, or other players they not only reached for but moved up to reach for.
By the way, Clay Matthews is really Clay Matthews III. How come he doesn't have a III on his uniform like Robert Griffin III?