As part of a project I'm working on, I applied the TrueSkill rating system to FRC data this year, here is some data showcasing it for teams at IRI:
https://gist.github.com/jhtervay/db4...eb9c38bc51d9b7
This does not include any offseasons. They are not reliable enough data sources for this type of model. The initial rating is 1500.
If I'm missing a team, let me know.