I know this has been brought up here before, but the question is how a program that recruits at the very highest level can have such a short bench that they're "tired".
Several specific reasons for THIS year, and one general reason for Duke:
The Amile Jefferson injury has shortened their roster and thrown off their rotation considerably. He has missed a long portion of the schedule and really, no one has stepped up.
One 5-star, Chase Jeter appears currently to be over matched. He's really not ready to play much but has been pushed into more minutes than he is capable of handling.
They probably weren't ready to lose their freshman PG last season after only 1 year. But, after a great Finals, he was drafted. It is REALLY hard even for a blue blood program to lose most of their stars every year and plug in big-name freshman.
Kids used to be reluctant to sign somewhere they would be sitting behind other stars. Teams sometimes used to have almost bi-modal recruiting, stars and practice players. Duke used to keep their stars for several years and rarely recruited many kids not able to be stars. We need a full roster becuse our recruits need time to develop. They really didn't need a 13 man roster because most of their recruits were ready to play early.
If everyone is healthy and no one is a miss or bust, all is well. When they have one of each, even Coach K can have problems like mere mortals.