Not all concussions are created equal. Some occur with loss of consciousness; others without. Some lead to minor side effects and others to long term issues. In fact the NFL is now grappling with a condition called traumatic encephalopathy which occurs after repeated concussions or head trauma. This affects the brain and can lead to dementia, violent tendencies, seizures among other things.
Problem is that at the present time there is simply no good way of grading how serious a concussion is. If you base it simply on whether or not there was loss of consciousness, or forgetfulness on scene. those factors may or may not result in serious consequences. Of course there is no issue when there is obvious brain injury such as a bleed or bruise.
Along comes some recent research which has identified two chemicals that are released with brain injury. What is thought to happen is that the injured brain cells or neurons leak out certain substances. The names of these two substances are long and boring, so I won’t mention them here.
One substance leaks earlier and doesn’t hang around as long as the other, which is leaked later but remains in the blood longer. Studies are now showing that levels of these substances correlate with need for brain surgery and longer term consequences such as memory loss. If these studies can be validated in a larger population, then the art of diagnosing a concussion will move toward a science-in my mind a better path.