If they take less from say a team in the AFC, then that team can go ahead with the deal and subsequently shuffle him off to Philly for an even better deal. What will we have accomplished then?! To get taken! The team that got him used us to trade him. It's a possibility.
IF the Cardinals were to take a lesser offer from an AFC team, they would surely include a "no re-trade" clause in the trade agreement!
I understand the logic of those who advocate trading Boldin to whatever team offers the best compensation. Theoretically, in addition to the Cardinals being strengthened as much as possible, the trade partner is being weakened as much as possible, so who cares if it's an NFC team? In fact, all the better to weaken an NFC opponent! And by that logic, why not trade within the division?
Given that the Cardinals are now at a point where they expect to reach the playoffs and contend for the Super Bowl, i think most NFL executives would be reluctant to trade a Pro-Bowl player to a team that has a good chance of meeting the Cardinals in the playoffs. The downside of taking a slightly lesser offer is less than the downside of being knocked out of the playoffs by Boldin's new team.
Hearing fans complain that "we could've had a higher draft pick" is nothing compared to what Graves would hear if an NFC team with Boldin knocked the Cardinals out of the playoffs in the next couple of years!
Considering offers from every team is the best way to drive up the bidding.
Taking the best offer from any team, regardless of conference or division, may be the most logical thing to do. But from a practical standpoint, a trade within the division is extremely unlikely, and a trade within the NFC would require a far better compensation package than a trade to the AFC.
...dave