Could it be April was just wacky, and the extent of Major League Baseball's effort to control the run scoring environment was overblown? Maybe, but it's hard to give them the benefit of the doubt after the lockout and the revelation the league supplied multiple types of balls last season. Still, it's worth looking at some of the early season numbers.
One of the biggest stories of the early going is the marked drop of homers, which dovetails into scoring. Two of the likeliest causes are the ball and the incorporation of a humidor in all 30 ballparks, up from 10 last season. Some other possible explanations are the abbreviated spring training and inclement weather in some locales. The unusual offseason, prohibiting contact between management and players may also have influenced the first few weeks of the season.
The problem with researching quandaries of this nature is there are too many variables to consider in such a small sample of data. With so many factors affecting how the baseball travels, it's impossible to unequivocally assign responsibility to the ball, or humidors. A few were cited above, with quality of each team's hitting and pitching also factoring into the dilemma.
Specifically, looking at how the humidors are affecting the flight of the ball in individual parks is an exercise in futility. Clubs have played around 20 home games, which simply isn't enough to flesh out biases such as quality of the home team's hitters and pitchers along with those they each faced. Data needs to be compared to the same team from previous seasons, but the roster composition is different, as is the schedule. Let's say hypothetically, the humidor reduces the flight of the ball in a given venue. If that team's hitters are better this season, or have faced inferior pitching, in a vacuum they'll hit the ball further than last season's group. If their pitchers are worse, the visiting hitters could hit the ball further than last year's early-season guests. As such, pinpointing how the humidor is influencing the distance is marred by the different samples of hitters and pitchers.
One way to combat the limited sample is combining all the parks using a humidor last season into one group with the other group being the parks employing a humidor for the first time. Unfortunately, this eliminates the understanding on how a particular venue is playing, and making fantasy management decisions based on that information, which is the Holy Grail of this process. The reason for this is the effect of the humidor isn't necessarily consistent from park to park. With the caveat this depends on how consistently each club stores the balls pre-humidor, in some places, moisture will be added to the ball (like in Colorado), reducing its flight, while moisture could be removed in other places, serving to add distance to fly balls. It may even be the two balance out, with the added distance in some venues being negated by losing distance in the others, yielding the perception the humidor isn't exerting any influence.
Still, based on the decline in average fly ball distance this season, it's worth designing a study of this ilk. At minimum, would the reason for the reduced flight be attributed more to humidors, or the ball itself, leaving it up to the fantasy manager to extrapolate the findings to each park?
The other reason for undergoing the study is there has been some intriguing information regarding the ball and the possible repercussions of the humidor. In brief, Dr. Meredith Wills, an astrophysicist who has been at the forefront of studying the ball over the past few seasons has surmised transferring baseballs in and out of the humidor may be non-uniformly altering the moisture in the outer strings just under the cover. Doing so may be the reason flat spots have been reported on some balls. In addition, if the strings absorb moisture, the expansion could be forcing the seam height to slightly increase. Both add more drag to the ball's flight.
Another aspect to research is average exit velocity of fly balls. If the velocities are close to last season, drag is the more likely cause of reduced flight. The reason for a change in velocity, however, could be a different ball, or how it is affected by the humidor.
Here is some leaguewide data, showing the decline in average fly ball distance.