The first coach I ever interviewed didn't believe in yelling at athletes. He didn't think negativity worked at any volume, in fact, at least not over the long term. He coached college track and field and taught sports psychology, and to my knowledge always practiced what he preached.
This first interview was in 1984; I was a freshman in college just learning how to be a reporter. In the 32 years since, I've covered hundreds of coaches in multiple sports who've run the gamut on the "screamer meter," ranging from, "It's actually counterproductive" to "It's always necessary."