The head fault comes in many flavors, sizes, styles, and brands. And this aberration of the neutral spine is best expressed by the ubiquitous "chicken neck."
When under athletic demand, we want our athlete's head to be in a position that reflects both utility (have to keep my eyes on the ball) and "best" neutral spine positioning. Deviation from neutral, straight spine can cause a whole slew of silly mechanical BS downstream (blown cervical discs, flexed lumbar spines problems, poor shoulder positioning, etc.)
Best defense? No be there.
See if you can identify the chicken neck in the movements below.
Coach Kstar