Darry was a sportsman who was capable of attaining a sports scholarship to take him to college. Likewise, Ponyboy is talented at sport, though he is a good track runner whereas Darry was a footballer.
Darry had to leave school to look after his brothers after their parents were killed in a car accident. He is devoted to his family, as Ponyboy is. Darry can see that Ponyboy has the potential to leave the Greasers and become his own person: Darry himself had this opportunity but chose to delay his future to support his family.