rambling.
I say play whoever is the best and has the best grasp on the system. However, I think that more often than not, that person will be an upperclassman. If it's not--then go with the young talented guy. My opinion is more an indictment of the player development that's occurring...not who is being played.
All of this being said, I think that if the coaching staff put in a system where players are being developed then they'll by sitting for a couple of years and learning.