Tactics - When to change direction

I've watched a few tournaments and I always see them doing this: Rallying. What I mean is that they return the ball to the opponent on the same side they are on. What is up with that? I mean they could just return it to the other side of the court and win the point. Could someone explain this?

Also I am Charles. I changed my name to Charlie to be more personal. Thanks.

Hi Charlie,

Players often play back across court because then they don't open up the angle for their opponent. 

If you change direction with a weak stroke your opponent may be able to hit the ball away from you on the next stroke.  What you need to do is wait till you get a weaker stroke and then change direction.

You will notice this happens even more with the top Women players.