March 3, 2005

Crooked Numbers

The Morning After

by James Click

If you're heading down to Florida or Arizona in the next month, you'll surely be taking in a few spring training games here or there. One thing you won't see is extra innings. Much like the occasional All-Star game, spring training games sometimes end while tied. This is typically fine with everyone because teams aren't there to win the games, they're there to determine their roster, work on the fundamentals, and get a nice base tan. No one wants to get hurt and no one wants to get too tired, so after nine innings are up, everyone goes back to the batting cages or the golf course and has a great time.

During the regular season, things are obviously different and it's clear that extra-inning games can be a drag on a team. Playing nine innings every day is hard enough, but throw in the occasional 13- or 14-inning affair and players can show signs of fatigue, particularly in the bullpen or behind the plate. Managers find themselves with fewer options than normal the next day because players are still tired from the previous day. Doubleheaders have similar effects on clubs. Free baseball is great for the fans, but it can be rough on their team.

Just how much the extra innings affect a team is difficult to gauge. Looking at winning percentage in the following game doesn't reveal much because often the same two teams who battled through the long yesterday are playing again. Teams that played extra innings or a doubleheader and then play the next day are going to have a collective winning percentage of .500 no matter how tired they are or how many extra greenies are in the coffee. Instead, we must look at situations in which one team played extra innings the night before and the other did not.

In 2004, there were 218 extra-inning games. That may seem like a nice sample size, but 105 of those games were only 10 innings. Let's push ahead anyway and see what we find. Looking at all teams in 2004, we can find 89 games in which one team played extra innings the day before and their opponent did not. In those 89 games, the tired team--for lack of a better term--won 38 games for a winning percentage of .427. While that may seem to validate the idea that tired teams don't do well the next day, it may simply be a case where those tired teams happened to be very bad in general.

To correct for this, I've weighted the overall winning percentage of our tired teams by how many games they played and how good they were in general. For example, the Diamondbacks played in four such games, so their winning percentage--which looks a lot like a batting average--is counted four times. Add up all the teams like this and the teams in these 89 games had a weighted winning percentage of .505, nearly 80 points higher than their actual winning percentage in those day-after-extra-innings-games. Looks like we could be onto something.

Before we get too excited, let's see how things shaped up over the past 10 years:

YEAR   G    W    L   WIN %  eWIN %  DIFF
1995   99   50   49  .498   .505    .007
1996   78   32   46  .498   .410   -.088
1997  110   55   55  .502   .500   -.002
1998   99   46   53  .513   .465   -.048
1999   80   35   45  .516   .438   -.078
2000   85   41   44  .485   .482   -.003
2001   66   42   24  .508   .636    .128
2002   70   34   36  .497   .486   -.011
2003   97   53   44  .503   .546    .043
2004   89   38   51  .505   .427   -.078

In seven of the last 10 years, the tired teams have had a worse winning percentage than the fresh teams. However, throwing out years where the difference was almost zero--1995 (.007), 1997 (-.002), 2000 (-.003), and 2002 (-.011)--leaves four seasons in which the tired teams performed poorly and two in which they played very well. Overall, tired teams have a 426-447 record (.488) with a weighted winning percentage of just over .500. Tired teams perform just slightly worse than fresh teams.

The rest of this article is restricted to Baseball Prospectus Subscribers. Not a subscriber? Click here for more information on Baseball Prospectus subscriptions or use the buttons to the right to subscribe and get access to the best baseball content on the web.

Cancel anytime. That's a 33% savings over the monthly price! That's a 33% savings over the monthly price! Already a subscriber? Click here and use the blue login bar to log in.