Nothing. If they fight the exact same fight, the judges will know how to score the fight this time around. If we put that aside, Reyes needs to improve his cardio for one more round. If he wins the 4th round convincingly too, he can coast the 5th, nobody can take a 4:1 win away from him. Assuming that Jones can't improve his game for the rematch and will fight exactly like the last time.