I think a lot of us are missing the point.
The decision making doesn't go like: "If 1st round pick, I declare. If not 1st round pick, I come back."
The decision making goes like: "In which draft am I going to go higher?"
The argument for leaving is that the draft is weak, he may have reached his ceiling, and if he comes back a year older and isn't much better, his stock will plummet like it did for Sullinger and Terence Jones (remember that the NBA still drafts largely on potential).
The argument for coming back is that there's a chance he could be even better and will certainly gain more exposure next year than this year, when we've been banished to the Twilight Zone.
Of course, the X factor is the loyalty Bazz has to this program and to KO. That might sway him towards returning even if the dollar signs say he should leave.