This isn't the NFL or NBA. You don't tank a season on the hopes of getting some drafts picks and a better next season.
Go ahead and find me the coach who would start the less capable QB based solely on believing the kid will be a better QB the next season. I know it happens, but most of those guys don't last too long as HC's.
If the younger guy isn't up to the task of beating out the older guy, he sits until he can. Chasing future wins is no way to coach.