Yes, thats certainly true. Because of his background, he does know a lot more about football in general than fans who haven't been involved in professional football. He also knows more than virtually all the fans, about the playing side of the club.
However, these forums / fora are all about debate; hopefully considered reasonable discussion. Surely its not unreasonable to question the manager's decisions at times or are we going to shut that down? We cannot afford to suppress criticism simply because someone knows more than we do.
I was told by a former teacher to treat anything I was told by salesmen, lawyers, politicians and teachers with a questioning attitude. They might have silver tongues but they're not always right.
Constant criticsm for the sake of it is wrong but so is unquestioning support. Its a fine line to tread.