If one team is good enough to warrant beating another in 55% of its games, the weaker team will nevertheless win a 7-game series about 4 times out of 10. And if the superior team could beat its opponent, on average, 2 out of 3 times they meet, the inferior team will still win a 7-game series about once every 5 match-ups. There is really no way for a sports league to change this. In the lopsided 2/3-probability case, for example, you’d have to play a series consisting of at minimum the best of 23 games to determine the winner with what is called statistical significance, meaning the weaker team would be crowned champion 5 percent or less of the time. And in the case of one team’s having only a 55-45 edge, the shortest significant ‘world series’ would be the best of 269 games, a tedious endeavor indeed! So sports playoff series can be fun and exciting, but being crowned ‘world champion’ is not a reliable indication that a team is actually the best one.
Leonard Mlodinow, quoted by Dave Berri