Neuroradiologist here. 👋🏻
The short answer is not necessarily.
I think the main reason for this difficulty on the imaging side is that the brain is such a highly tuned, precise instrument that doing small areas of microscopic damage (below the threshold of medical imaging to detect) can still result in noticeable dysfunction (so a brain can look normal on MRI but have damage too small to see). Secondly, the MRI appearance of chronic trauma overlaps hugely with other, more common conditions.
In a research/university setting there is improved ability to detect some of these cases using advanced or experimental techniques that aren’t common out in the community setting, but even so I would wager that there are a significant number of cases that fall into the “looks normal” category.