Today In Baseball

By today we mean today compared to 19 games ago.  On August 23 (MLB uses the end of the day) the Cleveland Indians were 20 games behind the Dodgers in the race for the best record in Major League Baseball (MLB).  Today, 19 games later, the Indians are four games behind the Dodgers in the race for the best record in baseball.  It matters because the team with the best record will get home field advantage in the World Series.

It is amazing that the Indians have won 19 in a row.  It is perhaps as amazing that the Dodgers have lost 16 of 19.

Sidebar: Excel has a binomial function.  Since ties are extremely rare in MLB, the binomial function works well for explaining baseball streaks.  One problem is determining the true winning probability for a team.  Should we use the winning percentage before or after the streak?  A second problem is the independence of consecutive baseball games.  Baseball, like almost all sports, has momentum so it doesn’t fully meet the independence requirement of the binomial function.  On the other hand, the list of winning streaks suggests that the binomial function is a pretty fair approximation.  In about 140 seasons with, say, 20 teams per season the longest winning streak without a tie is 21 games.  The probability of (21,21,.6) is 0.0022 percent.  One event out of 140 times 20 is higher, 0.0375 percent, but both numbers are tiny.  End Sidebar.

For the Indians the probability is 0.0061 percent assuming that they are a club that wins 60 percent of its games.  Assuming the Dodgers are a club that wins 60 percent of its games the probability of wining three or less out of 19 is 0.0101 percent.  If you think the Dodgers are a 70 percent team (they were .712 before the bad times) then the probability of winning three or less is 0.0002 percent. If you think that these events are independent then the probability of them both happening is the product of the two probabilities.  Independence is not unreasonable because the Indians didn’t play the Dodgers and they are in different leagues.  That product would be a truly tiny number.

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