It's not that the game is unpredictable always. Rather, it is since the thoughts of players, the way they handle the situations and their reactions at important times are so unpredictable that we often get to see unexpected results. And they are widely called as miracles as well.
Courtesy: Usain Bolt's Autobiography.
While reading through the Bolt's story the above lines popped up in my mind. I usually wait till the end of the read and then summarize my thoughts. But this one could not be stopped as it is so generic. At the same time I do believe that Bolt is not a miracle. He is a human being turned a brand with all his efforts put into his favourite ever, track and field. Not a miracle. And hence no correlation to him absolutely w.r.t. the above.