Helmets can't stop brain injuries. It's not a failure of equipment or technology or attention paid, it's a simple biological fact. Our old friend Mark Wilson has a wonderful breakdown of the technologies we have, and how they're simply not and can never be enough.
We've covered plenty of ground about the science of how actual brain injury works, but Wilson looks at how helmet technology is designed. It was originally based around preventing skull injuries, which were a fatal problem in football's early days. But these days, we're also concerned about what's happening to the brain inside the skull. And to that end, we can only do so much: