That rarely happens for any team.
Teams nearly always take a player at a position of need, and there are multiple guys that will grade out nearly as high as Peterson at positions that we really need.
You are correct. The top teams stay on top because they normally don't have any pressing needs and can draft for the future in the first.
Which brings me to this question: Do the Cardinals really have any immediate pressing needs that are greater than the secondary other than QB?
Scofield replaces Porter so taking Miller would be no different than taking Peterson when we have Toler. I don't believe the Cards feel they need to replace Levi Brown or Sendlein. Hadnot steps in for Faneca if necessary. They can get a very good ILB and/or an eventual replacement for Haggans in the 2nd or 3rd round. Keith is at RT with Bridges as backup. Wells and TH are set at RB. WR is fine for now. Wilson and Rhodes are set at Safety. So to me, in this pass driven league, greatly improving the nickel CB position is as big a need as any.
Its not like 2007 when they didn't have anybody to play Tackle and had to draft one and sign Mike Gandy as a FA. The Cards are in a unique position. They aren't drafting 5 because they had a depleted roster with a ton of holes like most teams drafting 1-5. They are drafting 5 because they had horrible QB play, several players in new positions, and poor defensive coaching.
So the Cards actually have multiple options in the first this year. Because as you say there are several guys who will grade out nearly as high as Peterson.
But for the reasons above I favor Peterson.