I think Ridley will start. I know we havent seen much from Murphey but I was never impressed with him. I think Ridley has potential.
I doubt Murphey gains more than 200 yards next year. He has never stepped it up before, and will now be coming off a knee injury. I think 90% of the rushing yards will come from Ridley/Shep/JJ/Ford.
This leads me more to believe that Montgomery won't even crack the 2 deep. Based strictly on DD's history.