With Demps, you have fantastic speed and he played RB at Florida for 4 years. If you put the ball in his hands and give him daylight, he will be gone. Instinct and moves come into play when he has to start finding holes, or setting up blocks, yada, yada, yada.
Also, you are again saying "not as X as player Y". That he isn't as polished as some players coming out of college doesn't mean that he doesn't have an understanding for the game. It's not like he's never played a down of football before.