A couple of thoughts -
1. Personnel decisions (especially about players you like but are worried about affording) are seldom made in a vacuum. They involve (a) other players on your roster at the same position, (b) who's out there in free agency, a trade or the draft, (c) the team's own budget/cap-ceiling issues, (d) what that player's presence or absence would mean within the context of the team's offensive scheme and the other players executing it. This Spring there's the added impediment of the potential lack of a contract and how this would limit acquiring guys thru trades and free agency.
2. I'm hoping the Cardinals learned from this past year's QB debacle - mainly that you should never take strength and depth at any key position for granted (i.e. let Breaston go - just like we let Q go - and our passing attack could very well start to crumple up domino after domino).
Bottom line - When you hear Graves and Wiz talk about the "core" group of players who define your football team, sometimes that core knows no boundary when it comes to position - i.e. you may wind up with 4 or 5 core players at WR. The lesson from a year ago, is - ignore the position-overload, and hang onto the core guys who make the team go. (i.e. Let them go at your peril).
In my opinion (from key grabs to his TD-saving TD from behind) Steve Breaston is one of those core guys and we'd be well-advised to do everything we can do to keep him.