I really like Jerami Grant -- think he's perfect. 2 more years after this at an commensurate salary (20M).
Why would Detroit want to trade him? If I were Detroit GM I'd be thinking Grant+ for Brown rather than Grant as the best player in the deal.
I'm pretty terrible at guessing what GMs would take in trades, but it seems to me that C's would have to start with Smart and then hope Detroit sees a very good prospect in one (or 2) of Pritchard, Rob, Romeo, Nesmith. And then draft picks.