Dak Prescott opened up on the death of his teammate, Marshawn Kneeland , on Thursday ... saying he wishes the 24-year-old "didn't have to go through what he went through." The Dallas Cowboys quarterback addressed the tragedy at a field dedication ceremony at his alma mater, Haughton High School in Louisiana ... admitting it was a "very tough day" for him. "Tragic loss," Prescott said. "I hurt. Heavy, heavy heart today. I hurt for Marshawn, I hurt for his family, I hurt for his girlfriend. I