Tailback is a crowded position at most places.
If find it hard to believe a 3-star player and enters a school with a strong program and would quit for lack of playing time. You are talking about a school where Travis Stephens had a minor role only to have the all-time leading rushing season his senior year.
Poole has three choices:
1) stay at TN, play on special teams, and work toward getting carries
2) Transfer to an FCS school and get a chance at starting.
3) Sit out a year and go to a Sun Belt or MAC school with the probability of not starting
There have many guys who have huffed off to FCS only to find out they don't get to start there either.
Don't assume Poole does not think option 1 is the most attractive.