Here's my opinion on "play calling." 

The plays we call during games change every week, by necessity.  We have an overall offense, which has a certain number of plays, which we practice during preseason.  Then every week, based on the opponent, the plays we practice and call in the games will change.  The essence of play calling doesn't occur during the games.  We have a game plan, and we believe certain plays will work against that particular opponent, and we practice those plays during the week before that game.  The offensive game plan is a collaborative effort between the offensive coordinator, the head coach, and the QB.  Then during the game, faced with a particular situation, a play is called that is part of that game plan.  The QB has the opportunity to audible out of that play to another play.  So the offensive coordinator is only partially responsible for the plays that are called and slightly less responsible for the selection of the play that is executed, because he's occasionally overridden by the QB. 

Game planning and execution are much more responsible for the success of the offense in any particular game than the play calling itself. 

I know a lot of you might respond, "I knew all that.  That's basic stuff."  But I get the impression some people don't understand how the decision is made to call a certain play at a certain time.  They see a lack of success, and they say, "They called the wrong play.  It was bad play calling.  If they had called this other play, it would have worked."  And that's shallow thinking, just one step up from yelling "YOU SUCK" from the upper deck.

---