According to the FIDE rules, after his defeat in the 1957 match against Smyslov, Botvinnik was entitled to a return match for the crown. Smyslov had to play Botvinnik again in the spring of 1958; already the third match in four years.
Moreover, already since the Alekhine-Euwe return match in 1937 the psychological dangers awaiting the newly crowned champion were well known. Kasparov also mentions this in his On My Great Predecessors series:
„ I know for myself how hard it is, on becoming champion, immediately to have to tune up for a new battle: you involunatrily feel that the main tests are behind…“
Also, Botvinnik was extremely motivated to get his title back and he prepared with all his might. He spent almost a whole year between the matches preparing, sharpening his openings and drawing the lessons from the previous match. Smyslov, on the other hand, was obviously unable to mobilize fully. The best indication of this is a story told by GM Vladimir Makogonov, who was part of Smyslov’s team. He warned Smyslov that Botvinnik might play the Caro-Kann, but the champion merely dismissed this with a wave of his hand.
Incidentally, out of the Botvinnik three opening victories in the match, two happened in the games he played Caro-Kann with the Black pieces. After capturing such an early lead, Botvinnik adjusted his match tactics and started playing incredibly cautiously – opting for safety first and foremost.
After 14 games, Botvinnik increased his initial lead to four points and the match was virtually over. A small ray of hope for Smyslov was provided by the infamous 15th game, in which Botvinnik’s flag fell in the superior position. Still, despite that error, Botvinnik maintained his composure and won the match after 23 games, with the convincing 12.5-10.5 score.
Thus, the endless Botvinnik – Smyslov battles of the 50s finally came to an end. As Smyslov himself put it many years later:
„I have the feeling that all my life I have been playing only against Botvinnik. I am happy to have played almost a hundred games against such a remarkable player. We were both in our prime, and I think that the creative results of our meetings played a far from minor role in the development of chess thinking. „
Sources:
Chessgames: Botvinnik – Smyslov Return Match 1958