Pruitt.
There have been some tweener-types drafted in the second round who proved to be stars - Monta Ellis and Gilbert Arenas come to mind. Unless you're a special player like those guys, though, tweener-types are so dime-a-dozen in the league, they really don't have value.
If his upside (best case) is basically to be another Eddie House, what's the point in keeping him around? He's the fourth PG, he doesn't seem ready to crack the rotation, and he's shown nothing to indicate that he can really be a star. You can always get a guy like this in free agency, for cheap money. No point in this team spending a roster spot on a guy who, maybe, can be the eighth or ninth man in another year.
Better to keep instead a guy who's still a legit PG (Cassell, even with his warts I'd trust him in there a lot more than Pruit), has a contract we need for trading purposes (Scal), or who can back up at a more needed position (Miles, Walker).
The only thing that saves Pruit is if Bill Walker proves to be good enough for Miles to be expendable, but I think they'll keep both of them.
If Pruit shows the coaching staff more than I've seen, maybe Cassell does get put on the bench in a suit and tie a year early. Have him keep in shape in case someone gets hurt. No reason the assistant coach can't be in the scrimmage, right?