For years – decades, really – the question of whether so many day games at Wrigley Field was a competitive disadvantage to Chicago Cubs players, who disproportionately would have to reset their body clocks to adjust back and forth between a “night game” schedule for their day, and a “day game” schedule for their day, was pervasive. It was frequently debated. I believe I heard “toughen up” a lot. I believe I said “shut up, you’re wrong” a lot.
In the last few years, players have finally been willing to concede that the constant readjustments do take a toll over time. Fortunately – for these competitive purposes, at least – the Wrigley Field renovations have brought along with them an increase in night games, and the Cubs are now closer to league average (though they still have about 15-25% fewer night games than the average team, depending on how many day games are picked up and flipped to night games by national media request).
I mention all of that as a precursor to a new study that suggests, setting aside the day game issue, that there may be another body clock issue that all teams are dealing with: constant time zone changes.
A new study has found that the impact of jet lag (defined in the study as traveling across two time zones) on player performance is considerable, particularly with respect to (1) reduced baserunning aggression (stolen base attempts and doubles) by jet-lagged players who’ve returned home, and (2) increased home run rates by jet-lagged pitchers (home or away). There are other potential impacts to batting and defense, though less obviously so. Further, impacts seem to be slightly more prominent when traveling east (whether going on the road or coming home), which makes intuitive sense, since game prep and game time would then feel “earlier” to the players.
This is fascinating stuff that we’ll all have to try to remember, anecdotally, as the coming seasons play out. Hopefully the Cubs are taking note and already working hard to figure out ways to ensure maximum sleep for their players, even in the middle of time-zone-bouncing trips, and especially right after they get home from a long trip (maybe send starting pitchers to the next location a day early?).
Note that the new CBA called for changes in the schedule that attempt to reduce the impact of jet lag by getting players to their next location long before the next day’s game is to begin. That likely means more day baseball for the rest of MLB, starting in 2018, which is nice for the Cubs.
Also note this Hardball Talk table on the travel schedules for MLB teams, for which the Cubs’ central location reduces their travel a great deal (fewest miles traveled in baseball last year). That’s not quite the same thing as a proxy for jet lag associated with body clock adjustment (for example, teams in the west have to travel great distances to play each other, but they aren’t changing time zones in the process), but, even as a separate issue, I’d imagine that longer and more frequent plane trips is probably not great for the body either. (Cubs free agent selling point!)
All in all, the study is an interesting addition to our mental file about how less obvious things about the humanity of players can impact their performance on the field.