Aaron Curry is a rookie and because of the flawed rookie scale, he will be grossly overpaid.
With the uncertainty of the market next season, Dansby would be wise to sign a deal this season. The going rate for a pro bowl linebacker is 6 years 50 mil w/ 20 mil guaranteed, a la James Harrison and Bart Scott. This is down from paying one hit wonder linebackers like Calvin Pace $22 mil guaranteed last season. I believe the Cards were prepared to pay him more than Harrison when he fired his agent.
Dansby is gambling if he doesn't get a contract done. He has yet to make a pro bowl (alternates don't count). If he has another non pro bowl year or gets injured somehow, with the uncapped year, he may get screwed.