There was also the little fact that Kasparov was not playing his top chess in the 1997 match - the loss in the sixth game was considered very bizarre at the tim

There was also the little fact that Kasparov was not playing his top chess in the 1997 match - the loss in the sixth game was considered very bizarre at the time (him going for the Caro-Kann, while not having much experience in that opening) His rematch against Deep Junior (the 2003 computer) ended in a 3-3 tie, so humans were actually able to hold off computer for quite a bit longer than 1997...