Byrd's calculation to call a stoppage was likely not based on signs of fatigue, but rather signs of traumatic brain injury. Ataxia, or dizziness and loss of balance, is one of the hallmarks of concussion, a type of mild traumatic brain injury. Fatigue may cause sluggish and slow movements, but does not cause the imbalance and poor coordination exhibited by McGregor in the 10th round. Being wobbly, in the setting of pugilistic trauma, will always be treated as the result of head trauma and not as fatigue. To let a fighter continue on would be grossly negligent.
