Every player has a certain value. The issue is convincing him that his personal assessment is more than his actual worth.
It's human nature to desire to be compensated as much as your counterparts at the same position. However, this is generally not feasible in the modern salary-cap era.
Occasionally, prior production makes it difficult for the contributor to look past his most recent output.
Whatever the reason, these guys will have a difficult time finding the money they want.