ditto on SBK comment.
Many times learning is based on "vocal emphasis". You're outside, in a team environment, and you don't always have the luxury to learn by experience. How do parents get that point accross in similar situations, we call it "raising our voice". I find it ironic that coaches are reprimanded by mom/dad for doing what parents do thoughout the kids life. If it's not physical, and not blatent berating, it's called communicating and teaching.