Just think of if this way:

During the week, Shannahan and his offensive coaches study the Arizona defense. They see they like to play a certain coverage and identify key ways they can attack them using the players they have.

They gameplan a certain motion during a specific coverage that opens up Goodwin for a big gain. They get the look they want from the defense, and they set the motion up from the previous plays. The ball is snapped and everything is going exactly as Shannahan expected, Goodwin is open and then Beathard hesitates on the throw and it gets thrown in the dirt.

No matter how good the gameplanning was, or how perfect the playcall is, you need the players to take advantage of these opportunities. We saw Jimmy struggle this year but I see a big bounce back next year.