How does coaching work?

Most of the big names in coaching weren't spectacularly fantastic fighters themselves, so it's kinda weird that world champions respect their opinion on anything. Quick rundown on the head coaches and their professional fight records:

Andre Pedeirnas of Nova Uniao: 1-1-2
Rafael Cordeiro of Chute Boxe: 4-2
Mike Van Arsdale of Blackzilians: 8-5
Matt Hume of AMC Pankration: 5-5
Shawn Tompkins of Team Tompkins: 0-4

I don't think Greg Jackson, Duke Roufus, or Dave Camarillo ever even had a pro MMA fight. Pat Miletich of Miletich Fighting Systems and Randy Couture of Xtreme Couture make sense, being former UFC champions and all, but for the most part, most coaches didn't have very notable fighting careers.

But yeah, back to the topic, how do coaches gain the authority to tell a fighter, "You should follow X plan," if the coaches never experienced for themselves what following X plan is like in a real fight? If I was a fighter, I'd probably be quick to dismiss them as nothing more than armchair fight philosophers who talk out of their asses. Obviously, however, it's clear that these coaches know their shit, even though they themselves kinda, well, suck at fighting.