What position did Barry Sanders primarily play?

Which college was Jim Brown playing for when he entered the NFL? What jersey number did Jim Brown wear with the Browns? Which college was Walter Payton playing for when he entered the NFL? What jersey number did Walter Payton wear with the Bears? Which college was Barry Sanders playing for when he entered the NFL? What jersey number did Barry Sanders wear with the Lions? What position did Emmitt Smith primarily play? Which college was Emmitt Smith playing for when he entered the NFL?