Wednesday, January 26, 2011

Do Winning Streaks Create Momentum?

Fans, broadcasters and writers often talk about momentum within a game or over the course of several games.  A Tigers fan might get concerned, for example, if the Tigers are playing a game against an Indians team which had just won five games in a row.  The thought is that the momentum of a five game winning streak could carry into the next game giving the Indians an advantage.  On the other hand, the Tigers fan might be more confident if the Indians had just lost five games in a row.

A couple of years ago, I looked at the effect of a walk-off win/loss on the following game.  One might expect a walk off win to create momentum and make a team more likely to win the next game.  Conversely, a demoralizing walk-off loss might cause a team to perform poorly in the next game.  Using 13 years of data, I found no correlation between walk off wins/losses and wins/losses in games after walk offs.  Teams simply performed at the same level in the game after the walk off as they did in ordinary games. 

I recently worked on a similar study of teams with winning and losing streaks.  Using retrosheet data from 1995-2009, I found 69,182 sets of five consecutive games followed by a sixth game.  Table 1 below shows that there were 2,700 instances of a team losing five consecutive games, 11,159 times when they went 1-4, etc.

Table 1: Record in Game 6 after a Five-game Set

We can see that the better a team performed in the five-game set, the more likely they were to win game six.  For example, teams that went 0-5 won 45.4% of the time in the sixth game.  On the other hand teams which went 5-0 won 54% of game sixes.  So, at first glance, it looks as if winning streaks create momentum that carries into the next game.

We need to be careful here though.  We can't directly compare teams that lose five games in a row with teams that win five games in a row.  The teams that lost five in a row won 46.2% of their other games during the year.  This is similar to the their game six winning percentage of 45.4%.  Conversely, teams that won five in a row won 53.3% of their other games.  This is pretty close to their 54% winning percentage in game sixes.  The full results are shown in Table 2 below.

Table 2: Record in Game 6 Versus Overall Record

So, it appears that five-game losing and winning streaks do not cause teams to perform differently in the next game.  Instead, their performance in game six is similar to their overall record throughout the season.  To be more sure, I also looked at teams with three game losing/winning streaks and seven game losing/winning streaks.  The results were similar to those in Table 2.

So, the next time the Tigers face a hot or cold team, it might be better to look at the overall record of their opponent rather than worry about their short-term streaks.   

The information used here was obtained free of charge from and is copyrighted by
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