I don't want to fighter bash but imo Cain isn't and never was the best fighter technically at heavy.
He never really had any power, submissions, no real finishing ability. He adapted the Diaz style of pressure and volume, and I think that just mind fucked his opponents, and they were never able to set down in their head and really execute.
Thats why Mma is not only the greatest sport, but the hardest and most demanding. There are so many elements. In my opinion it is the highest form of any competition, it is the most complex platform of execution. there are endless factors, and I think fighting for a world title might be the highest high you can get