What are the odds of the best team winning the World Series or any seven-game series?
Let’s look at the probability of the best team winning the World Series. Obviously, this was much more likely before division play in 1969. The best team has a much better chance of getting to the Series based on a full season than on a playoff series. We can’t figure out exactly what the odds are of the best team winning. But if we take a sample for the years 1961–1968, using our simulation and assuming that the true winning percentage of each team was downgraded 20% toward the mean and that the best team was the team with the highest percentage, we get these results (where the probability of winning is based on 1,000 simulated seasons):
year AL winner wins prob of NL winner wins prob of winning winning 1961 NY 109 .730 CIN 93 .497 1962 NY 96 .551 SF 103 .373 1963 NY 104 .766 LA 99 .565 1964 NY 99 .385 STL 93 .254 1965 MIN 102 .616 LA 97 .414 1966 BAL 97 .644 LA 95 .382 1967 BOS 92 .306 STL 101 .709 1968 DET 103 .781 STL 97 .649
This says that, on average, the best team in the league wins the pennant a little more than half the time, which seems reasonable. The best team overall increases that probability to around 60%.
We already stated that the probability of winning a given game is equal to . 500, plus the difference in winning percentages of the two teams. Extending the series to three, five, seven, or nine games increases the odds of the best ...