It is not easy to avoid the female player in mixed.
She will spend more time at net, and the women often play very close to net. Say I am receiving the 4.0 guy's serve in the deuce court. How am I supposed to take that serve and re-direct it at the woman well enough that she won't have an easy volley put-away?
Also, remember that doubles players have patterns of play that they prefer. Returning crosscourt is the bread and butter, as is hitting to the player who is deeper in the court and driving the ball up the middle. These strategies won't steer the ball to the opposing female. Then what?
-- Random Error Generator, Version 4.0
-- Master Moonballer