Ever wonder why a team starts every game with a running play right into the middle of the defense? Do you think to yourself “Don’t they know this play isn’t going to work?”. Most people have that same thought. Now if by “work” you mean score a touchdown, then no it’s not going to work 99% of the time. Or maybe you meant gain a first down or at least positive yards by “work”. And even then, the play probably is not going to work 80-90% of the time. It’s all about the mind.
A team will usually start each game with a run play up the middle to keep the defense honest. Said another way, to get the defense to expect a certain play from the offense. It is obviously helpful for the offense if the run play up the midde gains a lot of yards, but that is not the main purpose. At the beginning of the game the offense wants to show the defense a certain set of plays. If the defense cannot stop them, great. If the defense does stop them, now the offense has seen how the defense is defending certain plays.
Later in the game, the offense can run different plays out of the same formation they used to execute the run play earlier in the game. With the defense expecting a run play up the middle, the offense can call a pass play and catch the defense off guard.