@Eleuthero #11 If Carlsens opponents would have played as weak as Fischers opponents at that moment in time, especially Larsen, who blundered a pawn in the opening in one game, or Taimanov who blundered a rook five moves after restarting an adjourned game, then Carlsen would also have won these matches 6 0.
Still, a winning strike of 20 games - 7 in the last rounds of La Palma, then 13 against Taimanov, Larsen and Petrosian - is of course unreached in chess history and Fischer deserves respect for that.
But Fischer did not defend his crown against Karpov (who was top fit at that time). And against no other reigning World Champion. In that sense Fischer was just a one-song starlet.
Carlsen has always defended his title, and if he doesnt lose interest in chess he will still do it in 25 years :-)