Well, it's official - or is it really? Apparently, the 76'ers Markelle Fultz has been diagnosed with Thoracic Outlet Syndrome, which may be all, or part, of the reason his shooting and career have been side-tracked.
This is a condition where blood vessels or nerves between the lower neck and first rib are compressed, leading to shoulder and neck pain and numbness in the fingers. Two possible causes of the condition are trauma or repetitive activity (per MayoClinic.org):
Trauma.