Let's look around the league and try to find a player who compares favorably to Grant .... what's the blueprint for Grant finding success at this level?
The names that typically come to mind are guys like PJ Tucker or Boris Diaw.
Trouble is Grant hasn't shown himself to be a consistent (or willing) enough outside shooter, nor is he really quick enough, to be a full time perimeter player. On the other hand, he isn't nearly as big (thick) as a guy like Diaw, which limits his ability to be a playmaker or scorer inside.
I think Grant would need to become a much better shooter, or else turn into a much nastier / more physical defender, in order to find niche in the current NBA.