This is an obvious counter-argument to this post, which argues for trading our backup quarterback for what we can get for him.
Honestly, however, I don't think Mr. Stanger's position is all that far from mine. If we get a second round pick for Matt Flynn should we trade him? Absolutely! And I might do a deal for a high third. At some point another team's offer is good enough to move Matt Flynn. Take the money and run!
The question is: Will we get that second or third round pick in exchange? I tend to think not.
My take on the situation is heavily wrapped up in the notion of "surplus value", which the guys at Fangraphs have been pushing on the baseball side of things. A player has a value, $X, and a contract, $Y. His surplus value is then S=X-Y. (To be fair, $X can be different for different teams and schemes. But that doesn't play into later analysis in this case.)
Every team in the NFL got a chance to kick the tires on Matt Flynn last year. And, aside from the Seahawks and Dolphins, no one made him an offer. The Seahawks made the best offer, which indicates that the Seahawks paid above what any other team in the NFL would be willing to offer for Matt Flynn's services. This means that Matt Flynn has no surplus value to other teams.
Let's couple that with two salient facts: (1) The Seahawks have cap room to exercise, and (2) the Seahawks are in a position where a competent backup quarterback has high value. I think the Seahawks still value Matt Flynn's services more than his current contract's liabilities. That is: He's still a surplus value proposition for the Seahawks.
In the end the argument that I'm making here isn't, "Don't Trade Matt Flynn." (Although it's fun and provocative to put it in those terms!) It's more along the lines of: "No team is going to offer the Seahawks enough value to offset his current value to the team." The market for Matt Flynn was established last off-season and not much has changed it. I don't see any team laying out enough value to make John Schneider open up his grip and let Flynn fly away. And really, that's okay. Matt Flynn has value to the Seahawks right now.
Okay, there's a fly in the ointment, here: This argument presupposes that there isn't a team out there offering a valuable player who's a cap liability. The Seahawks have cap room, and it's going to expire soon. If another team offers a quality but expensive player for trade, the Seahawks might do the deal. I'll leave speculation on the identity of such a player as an exercise for the reader.