Isometrics force time under tension. Isometrics at the end range consist of actively contracting the muscle while the limb is in a stretched position. This means prolonged engagement with the muscle. Muscle engagement coupled with active contraction leads to enhanced muscle recruitment.
This could explain the heightened mind-muscle connection experienced during overcoming isometrics. But it would not only be contraction coupled with activation, rather engagement and mind-nervous-system activation which would enhance the development of the muscle with proper balance of the load.
There is already evidence that stronger people have more involuntary muscle activation. And it is so for a reason, how else can one remain strong without exploiting everything and losing out on mass?
Enhancing the effectiveness of muscle training by bettering the efficacy of the mind muscle connection is paramount. Each fiber needs to be engaged properly and the only way to properly engage every fiber is to have a sufficient connection between mind and muscle.
Thus, the methods and training techniques and workouts developed by Scott using overcoming isometrics could lead to proper engagement of every muscle fiber without wasting any muscle fiber, just due to the added engagement of all receptors in the muscular tissue.