I won't start panicking until the middle of the season if he still hasn't started to contribute. Here's a thought experiment; the next 5 (6 actually but here was no way the Bengals were taking a QB) selected after Murphy. Who would you have rather had? I know teams have different rankings but hey can't be THAT far off:
Bryan Bresee DT
Nolan Smith EDGE
Felix Anudike-Uzomah EDGE
Joey Porter Jr CB
Sam LaPorta TE
I may have gone with Bresee* or Laporta but I'm giving Duke the benefit of the doubt as of now.
* I meant Porter, no idea why I typed Bresee. Leaving the post as is and correcting.
That's the only thing that worries me, I'd prefer production over potential (I still think he will work out tho).
And on a side note, when you re drafting as late in the round as we were do you expect an instant starter?