I have a close relative with an acquired brain injury. In their own words, they 'look normal' but the reality is very different. Among other issues, they have significant cognitive difficulties with numbers, dates, times, and cannot multitask at all (including being unable to do anything whilst...
Loved him back in the day, a real anti-hero. For a while I tried a right-handed version of his bowling action but barely got it to turn an inch.
A great loss.