It used to be "Best Athlete Regardless of Position." But then it turned out that so-called "workout warriors" were being picked high, and while they could "do good shuttle", they couldn't play a lick.
This was adjusted by some coaches to "Best Player Regardless of Position" (i.e. can the dude play football?) - which means nothing more than - "If you had zero men on your roster and had to build from the ground up (and didn't place a premium on any one position - like QB), who'd you pick first, second, third etc.?"
"Drafting for Need" is just that. You feel your greatest need is at safety, you draft the best available safety.
Denny Green has gone out of his way to state that "need" will be a taboo word around the Cardinal organization before draft time. Assuming he's not blowing smoke - what he seems to be driving at is - teams that continue to chase "need" must consciously ignore really good players (because they don't need them to fill a position) and thereby don't maximize the over all quality of talent on the roster. (Note - This begins to really become apparent over a period of years).
I've said in the past that I too believe in balancing need with athleticism by creating a modified board ranking "Best Player Available Among Several Positions of Need."
I say this because I believe there are few things more frustrating than a team with, say, 4 Pro Bowl running backs but really sucky offensive tackles. Best Athlete proponents would, no doubt argue that later on you can always trade your surplus players for guys who can fill needs. But, based on team history, I don't think the Cardinals always get maximum value for the players they have to let go.