Too Tough to Take Down
I have said it before and will repeat it; when skill sets are equal or similar, the stronger, faster, and more athletic athlete almost always prevails. If you have to bet on a fight, and all you know about the two fighters is that they are equally skilled in martial arts, but one athlete squats 800lbs while the other squats 315lbs, who would you bet your life savings on if you were forced to?
When skill and technical ability are practically equal, as they usually are at the top of any sport, absolute strength and athleticism make the difference.