Here is the important point. Crawford should be willing to sign for less now then he will after this up coming season. How much less we can all debate until we are blue in the face but anyone with common sense should know Crawford would rather have a new deal now then to wait an extra year. There is a value to that and that value translates into a cheaper contract.
There is some gamble to the early contract for the Cowboys as well but I think it's worth it with Crawford. If I was going to pick a surprise probowl player on this roster it would probably be Crawford.