DF+you+cannot+win+without+the+ball

The expression, "you can not win without the ball" is stating that you need to have possession of the ball longer then your opponent to have the best shot at winning. In this case it is being used in mockery. The person saying this is the one who grabbed the rebound, he is showboating that he won the battle for it. Getting a rebound may be overshadowed by who is getting the points but rebounds are more impressive and you gain more respect. This is because getting a rebound means you beat out nine other guys who are trying to do the same thing and will do things that are illegal to get it. For this reason you usually get a lot of pride when you grabbed a rebound. It explains why you always hear basketball players yelling and flexing muscles as they get an offensive board and put it back in for the score. The saying is true "you can not win without the ball" and the way you gain possession of it is getting the rebound.

The poet may also mean that you need possession in order to try to shoot the ball and earn points for your team: teams only score on their actions, they don't earn points on mistakes made by their opponents (as they do in tennis).