I would definitely say yes, hardcore sport fans know everything about a team and will question often the decision of the coach. Good fans know the strength and weaknesses of all players and would be able to coach a team for a game. The difference between the coach and the fan is that it's the job of the coach do make decisions everyday. Being able to manage a team through the whole season is a tough job. It's hard to live with so much competition in the top football leagues, there is not much room for error. I don't think that the average fan would be able to be coach for a long period of time.
As a spectator it always easier to comment on a game after it, we know what went wrong and had more time to think about it. For the coach he has to make such kind of decision within minutes and he doesn't have all the information yet. If a player is having a bad day the coach could substitute him, but what if another player gets injured and he used all his substitute slots before? There is also the problem of favouritism, a coach might have a stronger bond with a certain player and will use him even if he is not performing 100%. Such decision will make the fans very angry if the team loses the game.