I agree you do what it takes for your team. But, at the end of the day, your production in the lineup is what matters-not your "moral support". Ask any of those guys riding the pine offering their support.
I could go into "If And and But" scenarios, but that could go on forever. I firmly believe there indeed is a time and place to get the crowd involved, but there also times when a player needs to focus on his/her on-field job and let the crowd be handled by someone else. Before stepping in the box is a no for me. After the base hit occurs-by all means let's go.
Take that to the mound for example. Do you want Gordo pumping the crowd before throwing to the batter or after he retires him? It only adds pressure to one's own self doing that before. The John Rocker mentality is only effective with a select few individuals.
From my perspective, the before-AB antics give fuel to an opposing pitcher as well. In this particular case with Mangum, had he not done that before that AB, the crowd would have been EQUALLY as fired up when he ended the 0'fer streak.