James Cook - Running back
First of all, James Cook is going to need to catch those touchdowns when Allen puts the ball in his hands. Cook was known as one of the best receiving backs coming out of college and has done very well in that department this season, so I'm not worried about him suddenly having an ongoing case of the dropsies. Cook might be the single most important player on this offense, not named Josh Allen. If the Bills can get their run game going with Cook and get him active in the passing game, that's going to make life very difficult for opposing defenses.
Cook became the first Bills running back since LeSean McCoy to eclipse the 1,000-yard mark. He finished in the top five in rushing and all-purpose yards. He's become one of the best backs in the NFL and the Bills need to feed him early and often. If James starts cooking, this offense is unstoppable.