A lot of people want to see the proof in the pudding.
Granted we shouldn't be judging a coach by his/her build it definitely says something if a coach is successful at what he preaches.
Just going off the top of my head...
Berardi has won Junior Nationals I believe in body building. Something of that sort.
He has also competed and completed in a triathlon (possibly more than one).
There is always a positive to getting info from someone who has "been there, done that".
Sure anyone can help you, but experience is a big part of coaching.