Johnson won't hire an OC to call plays because no one knows this system as well as he does. He could hire an OC to run the offense, but he will always call the plays. Frankly, I wouldn't want it any other way. His ability to modify on-the-fly is what has made him so successful over the years. I think he's going to look back at the season come back next year with a better approach than he had this year.
The day he hires someone else to call plays, I want a new head coach.
I like Johnson but my optimism has faded the last few years about us making a run at a national championship. I still feel like we can make runs at the ACC title every few years which ain't to bad considering the academic restrictions we face. I know this would never happen but I feel like Johnson would be more successful as offensive coordinator. Let someone else worry about the stuff he doesn't like and put all his knowledge totally in the offense.