Who won the rumble in The Outsiders? How was the winner determined?

In chapter nine, the Greasers face off against the Socs in a vacant lot and the two gangs participate in a violent rumble. During the rumble, Dally joins the fight and helps Ponyboy fend off multiple Socs. Towards the end of the rumble, Pony is kicked hard in the ribs and head. Pony mentions that he almost blacked out during the brawl before hearing someone yell "They're running! . . . Look at the dirty—run!" (Hinton, 123). Despite the fact that both gangs are severely injured and beat up, the Greasers win the rumble because the Socs were the first to flee from the lot. Pony recalls seeing the Socs members run to their cars before Dally grabs him and says that they are going to see Johnny. At the hospital, Dally informs Johnny that they defeated the Socs and Johnny responds by saying that fighting is useless. Although the Greasers technically won the rumble, the fighting between the two gangs will never end. Randy Adderson was right when he told Pony that regardless of the outcome, the animosity and conflict between the Socs and Greasers would continue.

The Greasers win the rumble because the Socs run off first.
The rumble has been set for seven o'clock. As Ponyboy gets showered and shaved and prepares himself, he talks to his brothers. When Pony asks his brother Soda why he likes to fight, Soda replies, "It's action. It's a contest. Like a drag race or a dance or something" (Ch.9). One of the others in the gang expresses his enjoyment of beating someone. Darry begins to have second thoughts about allowing Ponyboy to join the fight. He is worried that his brother has lost too much weight and is in a weakened condition. But Steve tells Darry, "Let him fight tonight. Skin never hurt anyone––no weapons, no danger" (Ch.9).
When the boys get to the fight site, other Greasers meet them. Just as the rumble begins, Dally shows up, using his one good arm to slug the opponents. Ponyboy gets knocked down, but he hears someone yell, "They're running!" He hears a voice yell joyfully. "Look at the dirty--- run!" Ponyboy tries to sit up, and he sees the Socs getting into their cars and leaving. So, because they run, the Socs lose the fight. Consequently, they will now have to stay out of the Greasers' territory.