Fantasy baseball players have a better understanding of advanced stats, granular data, and splits than ever before. Along these lines, most know that offense peaks in the summer months. Take your metric of choice, clearly ISO and wOBA are at their lowest levels in April before peaking between June, July, and August. Here is some data from 2022 and 2023:
This differential performance is largely attributed to warmer weather in the summer that allows the ball to travel further, leading to more home runs. However, weather varies from city to city. Using weatherspark.com, I compiled the average monthly temperature for all non-Dome teams for each of the six months of the baseball season. The table below shows this data and that baseball teams fall into three primary groups:
- Cold Spring and Hot Summer
- Temperate
- Dome
When we use these groupings and re-run our analysis, the data looks a little bit different. Teams that play in cold weather in April have by far the worst wOBA. Conversely, Temperate teams have the best wOBA in April and lowest wOBA in the middle of the summer. The Dome teams also perform well in April, but also spike in the summer, which appears a little anomalous to me. When using ISO instead, both Dome teams and Temperate teams experience a more consistent performance month-over-month. In fact, Dome teams and Temperate teams are mostly range-bound from an ISO of .155 to .165 all year.
What is the takeaway from this data? Last season, the hitting on my main event team got off to a poor start. A lot of the analysis on my individual hitters (Josh Naylor, Francisco Lindor, etc.) suggested their performance was largely fine, but they had been dealing with very cold weather in home games. If this is something we are aware of, shouldn’t we intentionally target hitters that play in temperate or dome environments to get off to a faster start (and the converse for pitchers)? While this type of analysis shouldn’t really be used to alter the core of your team (guys you are planning to hold all year) but you can use it to guide choices around your streamers or fringier players. This year, all the hitters on the back-half of my main event roster came from teams that play in temperate or dome environments (Ty France, Patrick Bailey, J.D. Davis, J.J. Bleday, and Richie Palacios). None of these players are necessarily off to roaring starts, but these types of decisions on the margins can push you over the edge.
