A few thoughts on the possibilities:
The situation: Palmer is scheduled to earn $13 million in 2013 salary from the Oakland Raiders under a deal inherited from the team's former leadership and renegotiated by its current one last year. Palmer could become available for trade or through release if the sides cannot workout a deal that makes more sense from a salary-cap standpoint. Palmer appears unwilling to rework his contract, according to ESPN's Adam Schefter. A timetable for Palmer remains unclear.
Forget about a trade: Acquiring Palmer would mean acquiring his contract. I cannot imagine the Cardinals acquiring a $13 million salary for a 33-year-old quarterback who ranked 29th in Total QBR last season at 44.7. That would make no sense, especially if the Raiders were going to release Palmer anyway. Arizona has been freeing itself from cumbersome contracts recently, not seeking them out. The team would have more than $20 million in 2013 cap space committed to Palmer, Drew Stanton and Kevin Kolb's old contract if the team acquired Palmer's current deal.
Palmer would help: Palmer has a 12-28 starting record with a 48.1 QBR score and 83.1 NFL passer rating over the past three seasons. He would still upgrade the Cardinals' quarterback situation. Palmer is close to an average starter, in my view. His reputation is better than that, but even if he's merely average, Arizona could use him. The Cardinals got sub-backup play from the position much of last season. They rank last in QBR (26.8) and passer rating (65.7) over the past three seasons. They have zero or one viable starter on the roster right now, depending upon your opinion of Stanton. They need more than that, obviously. Adding Palmer would, in theory, give the Cardinals an average starter and a backup with potential in Stanton. Arizona could then feel better about the position heading into the draft.
Cap considerations: The Cardinals released Kolb, but the quarterback's contract is counting $6 million against the Cardinals' salary cap in 2013. Stanton, Brian Hoyer, John Skelton and Ryan Lindley are scheduled to count about $4.9 million against the cap. Any deal with Palmer would be signed in that context. Stanton has guaranteed money in his deal. Hoyer has a $2 million salary that is not guaranteed. The Cardinals have scrambled to fix their salary cap, cutting veterans before signing or re-signing 10 unrestricted free agents for less than $15 million in total cap charges. They would have the flexibility to sign Palmer on a shorter-term deal worth somewhere north of the $5 million per year Matt Hasselbeck recently got as a backup in Indianapolis.
Getting ahead of ourselves: If Palmer left the Raiders, Oakland could be in the market for a quarterback such as ... Seattle's Matt Flynn? Raiders general manager Reggie McKenzie was in Green Bay when Flynn was there. It's something to keep in mind.