Another point to consider.
Scenario 1: Pats assign franchise tag to Cassel.
Scenario 2: They don't.
In Scenario 1, the trading teams recognize that the Pats not only have no value in retaining Cassel, they have an enormous negative value and need to trade him. If Cassel stays, the Pats have $29mm in cap tied up in QB's.
So, realistically, what will teams offer? Certainly not two Firsts. Maybe a third? Let's assume it's a third for this argument, and folks can debate it.
In Scenario 2, Cassel enters free agency and signs with another team. We recognize that as a free agent, Cassel should gain a larger salary than in a trade. In a trade, part of Scenario 1, the trading team assigns a total value to Cassel and divides that value between the salary they pay Cassel and the value of the draft pick they use to trade for him. In Scenario 2, whatever that value is, all of it goes to Cassel in free agency. Thus, in free agency, Cassel should earn more money than the limited freedom under a franchise tag trade.
So, realistically, what would Cassel earn in free agency?
Matt Schaub signed a 6 year $48mm deal two seasons ago, or $8mm a year two years ago.
Let's just assume Cassel signs a deal averaging $7mm.
Under Scenario 2, then, the Patriots would be awarded a Third round draft pick for compensation for the loss of Cassel.
This analysis, then, shows that the upside to the Pats for the risk of $14mm in a cap hit is the difference between a Third and a Fourth round draft pick.
Is the drop-off between 2009 Cassel and 2009 O'Connell worth that risk?