There's no hope of a Summer League to make slightly less premature but far more certain pronouncements regarding Keith Benson, so I'll keep this brief. Benson blocked a ton of shots and posted fine defensive rebound rates at Oakland. Given those two facts and the league in which he played, his offensive rebound and steal rates are a concern.
He's skinny and he'll be 23-years-old whenever the 2011-12 season commences. His scoring rate, his age and his superior block rate in college makes him a better back-end of the rotation prospect than the equally unguaranteed Magnum Rolle.
Keep expectations modest and hope for some rookie and proven young professional free agent action to fill out the roster.