I will own it right here. I am a yeller. An incessant, loud yeller, at every meet and every soccer match. The kind some people don't like to sit next to because I'm liable to get too excited and dump a drink or popcorn on you.
BUT . . . I almost never yell anything negative. I will groan at a bad call in a soccer match if everyone else is, and I'll quietly tell another mom/dad that the judge was out to lunch if we do not think the score reflected their gymmie's unbelievably fabulous performance, but that is all. The rest of my yelling is all along the lines of "great job!" and I get as excited for the other kids competing with mine as for my own. My son probably hates this, but I will also yell out "great save" if the other team's keeper manages to stop one of his special airmail deliveries. I actually learned this before we got very far with gymnastics, because one of DS's long-term soccer teammates is now officially a former soccer player because of his dad, who was unbelievably negative and intrusive at games. DH gets very excited as well, but I've encouraged him to try to go by at least a 3-1 ratio (3 positive cheers must accompany every negative cheer).
Thanks in large part to this board, I now know better than to ask for a detailed rundown on practices, but I'm almost always ready to be a cheerleader when things are going well or a shoulder when they're not. If someone's down after a meet, I try to encourage focusing on the things that went well if the talk seems to be too much about the kip not made or the fall that never happens at practice.
Do you coaches out there think there's any harm in being vocal if it's positive?