12 Aug 2015
There has been a lot of press about the fact that last night was the first ever time in baseball history that all 15 home teams won. It was written about a bunch this morning and even made the national news casts. It’s a neat thing, but the fact that it has never happened before isn’t a surprise.
Start with the fact that baseball has had 30 teams since the 1998 season, meaning this is the 18th season that you could have 15 home teams win on the same night. Now estimate the expected winning percentage for a team at home. Let’s say 60% is probably the highest average you could justify. You would therefore expect all 15 home teams to win 60% raised to the 15th power. That’s would put the odds at roughly 1 in 2,500. If you assume that all 30 teams played on the same night 162 times a season, you would have had 2,916 times that all 15 home teams could have won on the same night since the expansion in 1998.
But it is worth remembering that if you have odds of 1-in-2500, trying something 2500 times doesn’t guarantee you will experience it. Vegas makes a lot of money off of people watching roulette wheels and expecting that eight-consecutive reds will result in the ninth spin being black, but it doesn’t work that way. Each spin has the same odds as the last. (And Vegas diabolically has two green numbers so your odds of black and red are not even 50-50 but about 47.5%-47.5% with a 5% chance that green comes up and ruins you.)
All of this is another way of saying I am bored and too depressed to talk about the Yankees right now. Hopefully, that changes tonight.