Did the D-backs, Dodgers suffer an inter-continental hangover?

Zack Greinke was widely panned in Australia for commenting that he had "absolutely zero excitement" about opening up the season in Sydney. At the time, Greinke explained that he just couldn't "think of one reason to be excited" for the games at Sydney Cricket Ground, and perhaps in part to avoid a negative Aussie reaction, he was left behind when most of the rest of his team boarded the plane from Arizona.

Greinke may have been on to something. After returning from Australia in March, the Diamondbacks won just nine of their next 29 games. But although it was much less publicized, the Dodgers also struggled; the team, projected for 89 or so wins, went just 11-12 through April 30 after taking the two-game set Down Under.

But six of both teams' games in April were against each other, obscuring the picture even further. Here's how both teams fared from March 30 through April 30, with their games against each other removed:

The Dodgers, like the D-backs, hit the skids pretty hard on their return from Australia -- it's just that their excellent performance against the D-backs helped to mask those struggles. Greinke, by the way, did just fine -- in fact, he won five of the Dodgers' 11 American wins through the end of April.

Here's how both teams have fared from May 1 through the games on June 18, still ignoring games that the two teams played against each other:

That's more like it. Both teams definitely struggled upon their return to the States, and with the NL West not looking like the strongest division in the NL (more hangover effect?), the fact that the outset of the season was dominated by intra-division games doesn't seem to explain that away. Sure, there are player-specific explanations here, including the DL stint of Clayton Kershaw; but it would be hard to draw the line between what might have had to do with the foray Down Under and what didn't.

To help zero in on what may not have have been luck, I also calculated the Dodgers and D-backs' wOBA by month, with the teams' games against each other in March and April removed. Note that league average this season is .314 wOBA, but the league average was .312 in March/April and .315 in May.

The "wOBA differential" that the Dodgers posted in May is essentially the same as that of March and April -- that suggests that the winning percentage change was probably more of a fluke, or I've guessed wrong on what the "hangover period" might be. Still, it's not like the Dodgers were better just after their return from Australia.

And there may be a good reason for why the Diamondbacks may have suffered more of an effect than the Dodgers: games played. From March 30 through April 30, the D-backs played 29 games -- and with the Dodgers playing just 25, that's a difference of four off days in a single month, roughly one per week. What's more, Los Angeles got the gift of rest early in the month; the Dodgers had a total of four days off in the first two weeks of the season. Arizona had just two days off in the entire month of April (on the 7th and 17th).

For next week, I intend to study the Japan series that have been played every four years since 2000 -- only then can we start to draw broader conclusions about whether there is such a thing as an inter-continental hangover. Methodology suggestions are welcome -- I'm tempted to focus more on position players, given that 40% or 60% of teams' rotations typically do not make these inter-continental journeys. And ask yourself this question: if you were running a baseball club, would you want your team to open spring training early just to open the season on another continent? I think we know how Zack Greinke would answer.

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All statistics courtesy of FanGraphs and Baseball-Reference.

Ryan P. Morrison is a featured writer at Beyond the Box Score, and co-author of Inside the 'Zona, a site on the Arizona Diamondbacks with a sabermetrics slant. You can follow him on Twitter: @InsidetheZona.