Yes, he was wrong, if he was in fact behind it. There was no way of knowing how Stewart would handle play calling. He hadn't done it the year before, but the offensive coordinator shouldn't stick his head into that situation unless he's a spoiled brat kid (to keep with the analogy) to begin with. And obviously, if Garrett had enough time to focus that closely on the defense, he might should have spent more time fixing his own playcalling problems.
Thankfully, Wade recognized it was a problem sooner rather than later and it was remedied.