While I agree with R. Graham that it is used to keep a defense honest and i agree that it keeps infielders from crashing on the bunt play, that can also be achieved by not showing bunt prior to the pitcher getting set and showing bunt while in motion or just after the ball has been released. I was taught to show bunt during the wind up or after the release of the ball, and even in a sac situation, we didn't square up to bunt until wind up and we got bunts down on a regular basis. I have seen with regularity this season, pitcher comes set, batter squares to bunt, pitcher delivers the ball, batter pulls back to hit. I get the strategy, I just think its dangerous