MLB lineup guides
Short, factual explainers on the rules and habits behind every MLB lineup.
Every guide follows the same approach: rules are explained from a named source, such as the Official Baseball Rules, and the numbers are our own calculations from Retrosheet data for the 2025 season, labelled as such. If you are new to lineups, start with when MLB lineups are released; if you want to know how to read our figures, start with what a start probability means.
- When are MLB lineups released?
When a lineup becomes official, why it can change before then, and what that means for projections.
- How managers set batting orders
The rules, the usual considerations, and how often batting orders actually change.
- MLB injured list rules
The 7-, 10-, 15- and 60-day injured lists, backdating, rehab assignments and roster effects.
- How MLB probable pitchers work
What "probable" means, why probables change, and how rotations really worked in 2025.
- What a start probability means
How to read the number, what calibration is, and how our baseline did.
- Platoons: lineups vs left-handed pitchers
Why lineups change against left-handers, with 2025 numbers.
More guides are planned, including doubleheaders and openers and bulk relievers.