Well, Philadelphia is where DBs basically go to die, and so I'm reticent to take his crappy play there and project it forward. Granted, when last we left Chung, he had really been struggling for us. But he was asked to cover a lot of ground alongside James Ihedigbo.
As Unorginal said above, with McCourty playing centerfield, we'd be asking him to do something a lot different.
I'm not saying I have a ton of confidence in Chung. In fact, I was killing on him in 2011, IIRC. But he is a good special teamer, so he's not a waste of a roster spot if he supplants Wilson or Ebner by playing better safety.
It's a harmless flier.