Sports is a good medium for socialization and development of a child. Aside from the physical benefits, it teaches many valuable lessons that would serve them well later on in life. Team sports help them learn to be part of a group and to realize that the universe does not revolve around him/her. They will learn teamwork, which in turn helps develop their understanding of cooperation. Individual sports are good for developing self-discipline and if motivated properly, help them learn to beat their worst enemy, their own selves.
However, I believe that a child should choose to be involved in sports. We may encourage them to take up sports but we shouldn't force them. Once they have decided to take it up, of course, I would like for them to do their best and be committed to it.
I think the distinction will lie in the sense that I will "push" (I prefer the words "motivate" and "encourage") my child to do well but in the context of giving his best, being committed and determined. The problem I think begins when parents push their kids to do well but do it in the context of a need to win, or where doing well is defined as winning and garnering awards. For young children, I think it is not necessary at this stage to burden them with the added pressure of having to win all the time.