I'm convinced the large fail ratio among scouts/Gms is due to overanalysis. The problem is the teams have too much info and too much time. The more info you receive the more likely you are to overvalue things that have nothing to do with football. Hackoli was great at doing this, as are alot of other GMs.
The game is played on the field - and what happens on the field is all that matters.
It doesn't take much info or observation to identify a player - But when it's your fulltime job maybe you start assigning too much value to things that have nothing to do with football.
The concept of thin-slicing comes to mind:
http://en.wikipedia.org/wiki/Thin-slicing
Someone with only a few minutes to perform an evaluation has a much more intuitive view of things.