Somehow, in only his 2nd season, I think Smart would be the obvious choice. As my coach used to say, "he's a man amongst boys", a natural born leader who's all-out hustle and tenacity rubs off on everyone around him. I can't think of anyone better than him to hold that title, except maybe Crowder or Bradley in a stretch.
Of course if I was CBS, I'd be hesitant to name anyone Captain if the best choice is a sophomore, if have no issue going without it.