There's a bit of a riff in the health and training world right now, between those who like to think of themselves as "field" scientists, and those who like to base their practices on evidence and research. And as in the case of everything in life, you have people at each extreme end of the spectrum, people who take advantage of those positions, and the truth lies somewhere in the middle.
On the one end, the evidence-based people are those who refuse to acknowledge possibilities unless there are numerous, broad spectrum and peer-reviewed studies confirming a concept. While evidence is valuable and necessary in order to help create new concepts and expand our capacity for learning - it can be limited because a) research takes time to do correctly, and b) sometimes we don't know what we're looking for.
On the other end, there are those who insist that the research is always behind what is developing in the "field", or outside the lab. They push concepts or "systems" that have no evidential support based on their own experience, and they forget (or ignore) the research, dismissing it if it doesn't support their beliefs.
So how are we supposed to know what to believe? Well, there's the rub - many times the people leading these positions are very charismatic personalities, with a powerful belief in what they're speaking of that makes it hard to ignore. Their conviction can be so powerful that it is hard to argue with them, particularly if we are less-educated on the subject.
As coaches, the best thing we can do is learn how to bridge the gap between the art and the science. Stop speaking in absolutes - what is taken as fact today may very well be dismissed 5 years from now when a new study comes out. Similarly, what works for one doesn't work for all, even if it IS and evidence-based practice. Stay open-minded, read the research, remain optimistically skeptical - and continue to learn.