i know someone who was an excellent power hitter in college and then he got extremely heavy (over 300 lbs). We were in a group taking BP at Shea Stadium and he was blasting balls up the gaps to the warning track and wall. When we congratulated him on his hitting, he told us that if he could have rotated his hips that he would have been driving those balls out of the park. He was hitting with all arms. No did not notice the hip rotation limitation by Panda, but I will be looking for it this year.