Playoff Chances After First 20 Games

This post is long overdue. It relates to something I heard on the Blue Jays radio broadcast of a game during the April 25-27 Red Sox series. Jerry Howarth, lead play-by-play man for the Jays, said that the Red Sox have never made the playoffs in a season in which they played below .500 for their first 20 games (i.e., 9-11 or worse). That is astounding. The Red Sox are an old franchise (113 years old; since 1901) that has enjoyed a fair amount of post-season success (22 trips to the playoffs). Not one of those playoff appearances came in a season where they started 9-11?

Well it is true. You can see for yourself here. The Red Sox have gone on to win the World Series twice after 10-10 starts. That one extra win is apparently crucial for this franchise. What about the other franchises? I decided to have a look.

Here is a figure I created using data from all franchises between 1901 and 2013. It shows the proportion of teams that have gone on to make the playoffs as a function of the number of wins they had in their first 20 games:

Playoff_20games

 

As should be expected, winning more games has lead to more playoff appearances. The decline we see at the upper end of the win scale is a function of only 5 teams having 18 wins to start a season, and 0 teams reaching the 19-win or 20-win mark. What is really striking to me (and relevant to this Red Sox discussion) is the change around 9, 10 and 11 wins. We see that 9.5% of the 347 9-win teams went on to make the playoffs, 12.5% of the 320 10-win teams went on to make the playoffs, and 19% of the 332 11-win teams went on to make the playoffs. We see another large jump around the 12- and 13- win mark. Getting those few extra wins in the early going appears to be at least somewhat representative of a team’s underlying ability and how they will play the rest of the season.

Often I encourage people to avoid overreacting to a team’s performance in April. And while that is still solid advice, this analysis provides some evidence that the first 20 games of a season can be a reasonable gauge of a team’s future. Obviously with more and more games played the end of season picture becomes clearer and clearer.

For what it is worth, the 2014 Red Sox had a record of 9-11 in their first 20 games.

Data obtained using the Baseball Reference Play Index.
Data table used to create the figure can be accessed here. Useful for seeing sample sizes.

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