Zombielanche

If you say “park factors” to semi-knowledgeable baseball fans they may cite Coors Field in Denver and it’s thin air, which is glorious in the eyes of people like Dante Bichette and infamous in the eyes of Mike Hampton. They may also know that Petco Park in San Diego is a pitcher haven where washed up veterans go to be reborn. And they may even know that Safeco Field in Seattle is hitter unfriendly, so much so that it drove away Alex Rodriguez.

Well this year, Safeco Field is the worst park on hitters in all of baseball. And since this is a climate change blog, you have probably already guessed the reason. It turns out the freaky weather may be dragging down the already lousy offense of the Seattle Mariners. The mighty Dave Cameron has some thoughtful analysis over at FanGraphs:

Doubles and triples are down, but it’s home run rate that’s really getting destroyed in Seattle in the season’s first three months. The Mariners hit home runs at an 86% higher clip on the road than they do in Safeco, while opponents are at 89%. In other words, Safeco is cutting home run rates for all players nearly in half compared to what they’re posting away from Safeco.

This isn’t a park effect that’s turning home runs into doubles either, as the huge BABIP gap shows that a lot of these balls that would be home runs are actually getting run down for outs. From an observational standpoint, it appears that balls are hanging up long enough for outfielders to get under them, so while the dimensions serve to keep the ball in play, it’s been the marine air that has turned those balls into outs…

For the country, the NCDC reports April average was 3.6 degrees warmer than normal, with only California, Washington, and the upper midwest reporting declines from the hottest March on record. May brought significantly warmer temperatures to the rust belt and to California, however, while it actually got relatively colder in the Northwest — Washington and Oregon were the only two states to post below average temperatures in May.

Looking at the AccuWeather recorded temperatures for June show that Seattle was still relatively cold, especially compared to the rest of the country. While the east coast is being bathed in 100 degree temperatures this weekend, the high in Seattle yesterday was 72. For the first few weeks of the month, the high sat in the mid-50s to low-60s. The Marine air serves to keep Seattle fairly temperate even in a normal year, but 2012 has proven to be abnormally cool in Seattle, especially relative to the rest of the U.S.

We know that there is some relationship between temperature and offensive environment in baseball, though it’s not a one-for-one tradeoff between heat and runs scored. Humidity is also a factor, and we can’t simply say that Safeco is playing as an extreme pitcher’s park simply because of the weather patterns in the northwest this year. However, as this article notes, Seattle’s climate offers two essentially two types of days in the summer – cool and humid or hot and dry. Humidity is highest in Seattle when its cooler, but as it warms up, the temperature gets further from the dew point. The recipe for a baseball to fly a long ways is hot and humid air, but that just doesn’t exist in Seattle. It’s either (kinda) hot or humid, but almost never both.

We have pretty strong observational data that shows that Safeco is suppressing offense far more than it normally does this year, and it’s probably not a coincidence that Seattle is one of the few cities in the U.S. that hasn’t really gotten around to having summer yet.