from one year to the next in terms of running ability?
Luke? Good from the start
Harvey? Good from day 1 starting his Soph year when he got the chance to play
Brown? Good from the start including 200+ yard rushing game as a true freshman
Willis? Good from the start
Jamaal? Good from start
Vision and instinct and flat out running ability is about as close to 100% instinct as any position and that cannot be coached to improve significantly. The things that can be improved are blocking ability, catching ability, knowing the offense better, etc.