The draft is very player dependent. Moving up to #6 doesn't make sense yet unless there is a difference-maker who slides to that pick.
I don't see any reason to give up assets and 13m of cap space for a PG when Marcus Smart is the future of that position, and for now we have adequate cover until he is ready in the form of Isaiah Thomas and Evan Turner.
13m of cap space doesn't sound like much, until you realize for 18m you can sign a max offer free agent star player. Taking away that 13m means you have one less opportunity to land a difference-maker on this decidely average talent roster.