For some reason, you value highly the POSSIBLE higher pick that we MIGHT get if we hold out until the week before the draft. However, you do NOT value highly having the $14.6M available for free agents starting on Friday. Personally, I would much rather have a #35-#40 this weekend than a #20 on the week before the draft or on the first day of the draft. In any case, I expect that we will also receive a conditional 2010 pick. BTW, I don't believe the value will go up, if at all, until the week AFTER the draft, when some team or teams will know that they have failed to get their quarterback.
You also seem to believe that the fact that Cassel has a $14.6M contract doesn't affect the price a team will offer for him. There is a limited number of team willing to tie up that kind of cap space, or even $10M a year for a four year contract with $20M guaranteed on what Belichick and the media are pitching as a young star quarterback. You may think that it crazy to pass up the chance to give a first, a 3rd and $10M a year for Cassel. Some teams have better uses for their cap money, and are willing to settle for giving a 3rd (or no draft choice for a free agent QB) and signing a QB for $3M a year, and use their first and $7M of cap room for THREE more contributers ($2M cap for the 1st and $2.5M each for two free agents plus perhaps a 3rd).
Cassel is surely worth more than Orton or Rosenfels, but I wouldn't give up my first round draft choice and two free agent possibilities to get Cassel over one of them, or one of the others available.
CONSIDER DETROIT
In both case, Detroit gets picks at 1, 35 and 82.
OPTION 1
Should they give up their #20, #65, and $10M a year for Cassel? or should they
OPTION 2
Sign a player at #20 with say a $2M cap effect for a 5 year contract
Sign a player at #65 with no cap effect for a 4 year contract
Sign a free agent QB at $3M cap for a 3 year contract
Sign another free agent at a $2.5M cap for a 4 year contract
Sign another free agent at a $2.5M cap for a 4 year contract
Somehow, unless I was really sure that Cassel would succeed as a pro-bowl QB, I think I would rather have a mediocre QB and FOUR more contributers to support him (in addition to who they pick at 1, 35 and 82).
Give a guy like Parcells or Belichick or Pioli OPTION 2 and they would build Detroit into a competitor in their horrible division within three years.
Why trade for a second now (unless it is the Chiefs' second and even then I would expect another high draft pick) when you can wait to around draft time and get a first and another pick. There are at least a dozen teams in this league who don't have a true starting quality QB. At least one of them will cave. There is no rule that says that Wilfork has to get an extention before the draft.
Belichick has not been known for being at the short end of the stick with a trade. I seriously doubt he will here. People were saying seven years ago that the Pats should just take a second or a third for Bledsoe to get him off the team. The Pats got a first and used that first to get Ty Warren.
Besides, if Rosenfels can command a fourth round pick, why wouldn't Cassel demand a first (or the Chiefs' second) and another high draft pick. Cassel proved more in December than Rosenfels has proven in his entire career.