Baseball Musings
Baseball Musings
October 02, 2008
Playoff Odds

The Hardball Times presents a new feature in which they post playoff odds every day. I find it interesting that despite losing a game, the Angels still have a better chance of winning the World Series than the Chicago White Sox.


Posted by David Pinto at 07:52 AM | Predictions | TrackBack (0)
Comments

Just noticed a story on mlb.com that first-game winners have taken 32 out of 46 division series since the format was instituted in 1995.

Guess what. That's almost exactly the percentage you would expect from a completely random binomial distribution with the probability of winning each game at 0.5.

There is a noticeable difference in results between the AL and NL. I doubt this is significant, but who knows?

Posted by: Casey Abell at October 2, 2008 12:00 PM

Oops, I goofed. The real numbers are 32 out of 52. That's slightly less than the pure chance probability with even odds of winning each game. But it's still pretty close.

Posted by: Casey Abell at October 2, 2008 12:04 PM

Went through a full decision-tree analysis to verify the simple BINOMDIST function on Excel. If odds were perfectly even for each game, the theoretical winning percentage in a division series for the first-game winner would be .6875. In the 26 actual LDS since 1995, the winning percentage for first-game winners is .6154.

Okay, real close. But the difference suggests what others have surmised, that baseball has "negative momentum." Winning a game actually hurts your chances in the next game, ever so slightly.

Or as Earl Weaver and many others have said, momentum is tomorrow night's starting pitcher. It's tough at the major-league level - and even tougher in the playoffs - to throw two starters back-to-back who are genuinely superior to their opposing pitchers.

Posted by: Casey Abell at October 2, 2008 12:33 PM

I'll get this right sooner or later. Of course, there have been 52 LDS since 1995, 26 in each league.

Posted by: Casey Abell at October 2, 2008 12:44 PM

Have Casey take math/probabilities instructions from ESPN Tim Kurkjian. Tim's MIT Phd father was US Army's No 1 mathmetician with statistics & probabilities his specialty.

Posted by: Bob S at October 2, 2008 09:56 PM
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