Rookie Watch: Best of 20

Golden State's Harrison Barnes has all the tools to be an offensive and defensive machine in the NBA. Rocky Widner/Getty Images

Two weeks ago, we rated the youngest age group in the NBA, teenagers all. Today, we continue our series ranking the rookie class by age with the 20-year-olds, who all have long careers ahead of them if they get some breaks. As a reminder, we are rating a player purely on the level of his ceiling -- how good he can ultimately be if given the perfect situation.