How Jet Lag Affects MLB Team Performance

Mark Lathrop

Wednesday, January 25, 2017 3:51 PM UTC

Wednesday, Jan. 25, 2017 3:51 PM UTC

Our expert handicapper, Mark Lathrop, is known for his betting analysis using sabermetrics statistics. In this article, he takes a look at a new academic study released that discusses the effects of jet lag on MLB players. 

A fascinating article has just been published in academia, which analyzes the effect of jet lag on the performance of MLB players in various situations. It can be found here, but let’s take a look at some of the big words of the abstract first:

“… Here, we examined the effects of jet lag, that is, travel that shifts the alignment of 24-h environmental cycles relative to the endogenous circadian clock, on specific performance metrics in Major League Baseball. Accounting for potential differences in home and away performance, travel direction, and team confounding variables, we observed that jet-lag effects were largely evident after eastward travel with very limited effects after westward travel, consistent with the >24-h period length of the human circadian clock. Surprisingly, we found that jet lag impaired major parameters of home-team offensive performance, for example, slugging percentage, but did not similarly affect away-team offensive performance. On the other hand, jet lag impacted both home and away defensive performance. Remarkably, the vast majority of these effects for both home and away teams could be explained by a single measure, home runs allowed. Rather than uniform effects, these results reveal surprisingly specific effects of circadian misalignment on athletic performance under natural conditions.”

Wow. Now those are some results that could be useful for an MLB sports bettor. The home team pitcher that traveled east and got jet lag gave up more homers. Now, in the nitty-gritty of the article the definition of jet lag is the crossing of 2 or more time zones without a sufficient time to normalize, i.e. off days. One hour per day is the time it takes to regulate your circadian clock. Think of an NL or AL East team traveling back home after visiting an NL or AL West rival. The surprising result is that the effects on baseball performance really present themselves only if you are traveling east. Here is another extract from the article:

“It is well established that the home team has a systematic advantage over the away or visiting team. In terms of winning percentage over the time period of our analysis, the home team won 53.9% of its games, corresponding to an advantage of +3.9%. In fact, the home-team eastward travel effect (−3.5%, P < 0.05) was comparable in magnitude to this home-field advantage (+3.9%). Thus, if the home team traveled two time zones east, and the away team was visiting from the same time zone, the home-field advantage was essentially nullified. On the other hand, the effect of traveling west was smaller and did not reach statistical significance…”

So, a team traveling east to its home park, without rest in between, loses the advantage of being at home for a few days. With sportsbooks often tilting lines to offset public betting on the "home-team advantage," this information is useful in looking at value of away teams in specific circumstances.

I’d also suggest looking at home-run rates of home pitchers in this west-to-east travel circumstance, given the player actually traveled with the team and not the day beforehand, as some starting pitchers do. If a particular pitcher is having a dinger problem, or an entire bullpen, the issue can be exasperated by jet lag. An increase in home-run rate of 1-per-10 games is actually quite significant, especially when looking at a data set of 4,919 games.

This is a fascinating study that I am sure will be discussed more as the MLB season begins -- I’m sure sportsbooks will read it and adjust accordingly! It will be fun to see if we can’t turn this science into greater profits as we make our MLB picks this 2017 season.

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