Listen to experts but don’t overestimate them. Just because someone knows a lot about a given subject a you often transpose this into a belief that they know everything. Concider the causality that when an expert talk about a subject they talk because they are the expert. Knowing a does not have to mean that he/she also know a lot about b,c and d.
I would say that it is most likely that he/she is the person in the group who happened to make some mistakes in this matter at one point or another and thus got to know what the problem actually means.
This is the no-magic you get from writing code and (importantly) exposing it to real life.
