True, which is why we try to use large samples for better context. But your point about tensing up is a good one. My mom's old timey "boyfriend" was an international level softball pitcher, and he's explained this to me many times. It's anecdotal, but it's logically sound: A lot of the times, he could see some good hitters tense and grip their bat like they were a Yankees fan trying to choke out Boone up in clutch situations. The occasion was rare when they wouldn't pop up a changeup because they were so anxious to get the ball out of the park.