defending runner at third

Question
What is the best way to prevent a runner on third base from scoring after a walk when the batter continues on to second base?
It is very frustrating just watching the batter "walk" to second.

Answer
Get the ball back to pitcher quickly. After a walk with a runner at third and second empty have the second baseman move so she is about 10 feet away from second just behind the baseline (between second and first). If the runner continues to second the pitcher fires the ball to the second baseman in front of the runner when the runner is about 5 feet away from her. Second baseman tags the runner out plus is still in good position to throw home if runner on third attempts to run home.

Practice this at practice to get the timing right for the runner sprinting to second and the runner walking to second (to draw a throw). I've gotten several double plays like this. Once a team sees you can defend this they rarely try it again.