Pitching exports advanced stats

[tbrittain]

https://library.fangraphs.com/pitching/

• FIP
• ERA-
  • Since we can't account for park factors, just calculate this by finding the league average ERA (adjusted to 100) and scale individual ERAs according to the average

[tbrittain]

Similarly to OPS+, ERA- will need to be restricted to the most recent season since it is dependent on the average ERA with all pitchers taken into account