You don't need to have ANY coaching experience to be able to evaluate. If one spends a decent amount of time learning the game from coaches, clinics, message boards, blogs, books, then they can become very knowledgeable. You certainly don't need any coaching experience to just have an opinion.
Whether one has only two years as a high school volunteer coach, or is an NFL coach, the game is still relatively uncomplicated. What makes someone an NFL or D1 coach is not simply that they know the game so much, its that they can get the most from their players (and they know someone or had a way of breaking into the higher levels). So what one's level of coaching experience really isn't relevent.
There are plenty of FBS coaches who get destroyed defending the Navy and Georgia Tech offenses. They try to defend it in a really unsound way. How can that be? They're the big dogs in the game. Its simple. They didn't put in the work to understand it or weren't able to come up with a way to defend it. Yet you have high school guys who know how to defend it.
I hope I'm getting my point across. You don't need any credentials to be able to point out an issue if you actually understand it.