He's getting a little long in the tooth to be called a rookie. And while the lack of playing time was clearly evident in his timing and decision making, there weren't many positives from a physical standpoint, which has to be a bit troubling for SD. His arm looked a bit suspect (as per his draft bio) and he moved around like a young Drew Bledsoe.
What I was looking for was the physical tools to suggest he'll grow into being an effective stater (just like with JP). From here, it looked like Rivers still has a lot of bridges to cross....