I've never understood that myth either. I mean, think about it logically. These guys are professional baseball players. Do we really think, I mean, using our brains now, that a few minutes of goof-off batting practice is going to alter someone's swing for the rest of the season? Or even a couple weeks? And then magically, during the offseason (an offseason where there's NO WAY the player would ever goof around with some friends and swing for the fences one day or even play in a charity softball game, right?) the guy's swing returns to normal? Really, folks.