McCourty has looked flat so far in his sophomore season, and Bodden has been... fine. Dowling showed potential, but not if he's fragile.
Arrington has been reliable, opportunistic, versatile rushing the passer, great tackling in the open field and seems to be the only guy in the secondary who has ball skills. I dont think Kyle is playing over his head, I think this is what he is... a tremendous find and a pretty reliable and productive player in a secondary that needs more of that.
I think you've summed it up well. I wonder if McCourty should be playing in the slot, assuming everyone is healthy. He's often been playing against taller WR's and he's struggled. If Dowling and Bodden are on the field against taller WR's or TE's I'd say let's put McCourty in the slot.