The D got wore down and part of that is due to the mental wearing down that can happen from refs impacting momentum. If the Lions scoop that fumble and return it for a TD, the D is on a totally different mindset compared to having the O fail to convert the TO into points.
It is a game of momentum. The adrenal rush can make all the difference, not to mention the change in confidence. No matter how "professional" these guys are, they are still human and emotions impact their play. The refs caused that high to be turned into a whatever. The rush was replaced by a crash, and that is never easily overcome. Even if that happened to only 1 guy, that is 1 guy who is not performing at their highest level and therefore vulnerable. So yes, the refs have ability to greatly impact a game.