Y is also partially determined by the employee. There is uncertainty from both the employer and employee on what the potential upside of Y could be. If an employee (programmer) believes his unique skills will be instrumental in making the company succeed, he won't discount Y as much as another employee (e.g. a chef just cooking the lunch meals for the programmers).

The potential employee programmer knows more than the employer about how good his skills actually are and how dedicated he will be which can affect the value of Y.