When you are playing doubles and both teams are playing up and back and you are the deep court player on your side, do you know your job?
 
Your job is to challenge the opposing deep court player by keeping the ball in play, not trying to move them too much or hit the ball by them. Wait until they make an error, pull you in to the net or hit to (challenge) your partner. Trying to move the deep player too much is a cause of many errors.
 
Your job, as the deep player, is to not challenge the opposing "up" player until they start "messing" with you (poaching). If the opposing "up player starts to poach too much, it is better to keep them honest by hitting behind them (down the alley) rather than to try hitting a greater angle cross court. This is where many errors occur. When going behind the opposing "up" player, you are not trying to hit a winner. You are showing them that you are paying attention to their movement. This way they will tend to hold their position and not poach so much. The lob is also a good way to stop the up player from crowding the net to poach.
 
Know your job as the "deep" player.
 
Good luck on the courts!