Why Has Back Face Signature (BFS) Been Removed?

Why has Back Face Signature (BFS) which measures the amount of helmet deformation on the inside next to the head after bullet strike, been removed from the Army Combat Helmet performance requirement? When the "behind armor" materials rapidly expand and come into contact with the human head, injury (concussion and or traumatic brain injury) occurs. Removing this performance requirement means we don't have a method to measure a helmets resistance to a high velocity bullet or fragment other than it passes through the material or not.  

We have allowed the requirement to be downgraded to accept a deformation material impact to the skull and the associated damage to the brain when data shows nearly 384,000 U.S. service members experienced a traumatic brain injury between 2000 and June 2018, 83 percent of which were classified as “mild,” another descriptor for a concussion.

National Research Action Plan on Traumatic Brain Injury and Psychological Health. The plan led to the creation of the Chronic Effects of Neurotrauma Consortium which studies the relationship between TBI, post-traumatic stress disorder and long-term neurological conditions.

Among the studies most relevant to service members and veterans published this year was research conducted by VA and civilian researchers at University of California-San Diego and Harvard University that found patients who experienced a concussion had a higher risk of post-traumatic stress disorder and depression after the injury, compared with patients who experienced a traumatic injury but whose head wasn’t involved.

I urge the US Department of Defense to look into why this critical performance critical has been eliminated (data collected for reference only) in light of the proven relationship before head impact and concussion and between concussion and Traumatic Brain Injury. The current design of a helmet pad set is not adequate to address the threat and has not been improved since the basic requirement was developed in 2005. This must be remediated in order to provide better protection to our Warfighters.

References; https://www.research.va.gov/pubs/varqu/jan2014/0114-2.cfm and https://www.militarytimes.com/news/pentagon-congress/2019/10/01/new-research-may-shed-light-on-combat-concussion-dementia-link/ and https://www.militarytimes.com/news/your-military/2018/05/01/shoulder-fired-weapons-can-cause-traumatic-brain-injuries-study-finds/