With Demby, IMO, the staff felt he knew the offense and that is why Demby got the start in Cleveland. Also maybe they felt moving him around during preseason is the reason he struggled. But I agree, he was not good, shocked they were able to win the game against Cleveland with Demby starting. As to Dominic Hatfield, very good on special teams, but again, cannot cover a bed.
Overall, it happens as a coach...You spend time with a kid, coaching him up, he does everything you ask and knows the scheme inside and out, which gives you false hope. You believe the training & education will kick in when the bullets start flying, sometimes they do and sometimes they don't and in Demby's case, they didn't. With the addition of Anchrum, I expect Demby to not get much playing time in preseason and to be cut, but sometimes the mistakes are made at higher levels in player evaluations like Coty Sensabaugh for example.