There's just no way he would have signed a contract like that with the REDS.
No way.
Nor would the REDS would have ever offered it, not with the state of the rest of the system as it is right now. They couldn't fill the pipeline fast enough (in their eyes with the way they do things) to take advantage of a contract like that, at least not in it's first three years.
That said, if I was the Owner of the REDS and Castillo was willing to sign that contract with us, I'd jump for joy. The next thing that would happen would be a mandate to Krall to shift the balance of talent in the system from hitting to pitching (those who make bats miss) and from the lower minor league levels to AA, AAA and the Major League levels. That's a tall task, but signing Castillo to that contract would be wasted if that task wasn't accomplished quickly, within the next 15 months.