In defense of Botvinnik (never thought I'd write this, since I'm a Keres fan): not having played for 3 years is a serious problem if you're playing someone like Bronstein, who was a great improviser over the board. As the games tell, Bronstein ran rings around Botvinnik in many middle game positions.
Botvinnik is rightly renowned for being harsher in his self-criticism than most GM's would be against their worst enemy. Unfortunately, Fischer's disparaging comments from his wounded ego (especially in the light of THAT game, where Fischer left the board white as a ghost, with tears welling up in his eyes) are given too much attention. My impression of Botvinnik as a chess player, despite all the things I dislike about him as a person (i.e a stalinist without culture and refinement who would use the system to his own advantage when he could), is that he had tremendous courage and a very profound understanding of chess positions. His legacy in various opening schemes is tremendous. Whatever else he did, he always played fighting chess.
when did Fischer left the board ??
And--eventually--overcame his opponents.