You're right. It's $8 mil in salary, $4 mil in bonus.
The deal can get done by converting almost all of that value into signing bonus and extending the contract. It's accounting gimmick, but it allows everyone to walk away happy. The Cards don't want to pay Rolle $12 mil for
one season. That doesn't mean that they don't want to pay him $12 mil on a long-term extension (which is actually pretty reasonable).
$11.5 mil signing bonus + Veteran minimum Y1; $1.5 mil Y2; $1.75 mil Y3; $2.2 mil Y4, $4 mil Y5 as an example.
That's a 5 year, $21.45 million contract extension with say the first two years guaranteed.
You're also wrong about Fitz's contract. Fitz was due to make $14.59 million in 2008, which put the Cards in a real bind. When they did his contract extension, Fitz cashed a $15 million signing bonus, and $17 million the first year of the deal.
See how that works out?