I think the primary reason that folks are nervous about the proposition of Phil Parker becoming the defensive coordinator is that there is a perception that the defense performed poorly in 2010 when Phil took over for Norm while Norm was sick. The Hawks had a number of future NFL players on that defensive unit and didn't play up to the expected standard. I think what people fail to realize is that while Norm was out, there were only 3, rather than 4, full time defensive assistants at the time. No matter what the industry is, adding 25% more work to the plates of several people is likely to hurt the overall product.
Maybe Phil isn't the best person for the job, but I trust that Coach Ferentz will hire the person he thinks is best for the program. I don't believe that he will ignore the best interests of the program simply to promote a friend.