An Unorthodox Opinion
When you look at most successful teams, the talent comes from everywhere (even Australia). If you doubt this, check out the last 10 years of Denver Bronco RB's.
It doesn't matter whether our talent comes from a veteran free agent, a top draft choice, a late draft choice or a UDFA just so long as we get it.
That said - obviously, you have better odds at bringing in great talent when you draft high in round one. But, as we all know, there are no guarantees. It's possible to bolo with your first pick and hit it out of the park in the next round. (Example: Johnson in round one/Q in round two).
As I see it, the Cardinals need at least one speedy cover corner, an impact WLB and a playmaking free safety on defense along with at least a couple of potential starters for the O-line. I don't agree with Skkorp about Leinart, but do feel we need to upgrade our #3 QB (and it couldn't hurt to bring in a young backup as "Leinart insurance.")
And - given the way injuries tend to crop up in bunches (let's not forget how lucky we were in 2006), there isn't a position on the roster that couldn't use more quality depth.
But whether any of these players come to us via free agency, the draft or anywhere else - it doesn't much matter. The first day a new guy puts on a Cardinal jersey, he starts fresh - with as good a shot at being a successful starter as anyone else on the roster