From Wrigley Field's Wikipedia page:
In April and May, the wind often comes off Lake Michigan (less than a mile to the east), which means a northeast wind "blowing in" to knock down potential home runs and turn them into outs. In the summer, however, or on any warm and breezy day, the wind often comes from the south and the southwest, which means the wind is "blowing out" and has the potential to turn normally harmless fly balls into home runs.
Time for some quick/lazy/unscientific analysis! Let's take a look at the average home runs given up by Cubs pitchers, sorted by month:
Over the past 40 seasons-- from which these numbers are drawn-- there does seem to be an uptick in HRs allowed per game during the summer. (March and October are small sample sizes, so don't look too much into those datapoints...)
But we don't know whether this is a Wrigley trend or just an MLB trend. There are plenty of reasons why homers rates might increase in the summer-- warmer air, players in midseason form, etc.-- so let's look at Cubs road games too:
Interestingly, summer home run rates don't jump in quite the same way when the Cubs are on the road. There could be a lot of reasons for this, but it seems plausible that the wind patterns do, in fact, lead to more summer homers at Wrigley Field. Would be interesting to see a more sophisticated analysis of this, especially one that incorporates the crosswinds mentioned later on in the Wikipedia article!
Comments