Automatic Runner
Extra innings start with a runner on second.
How it actually works. Introduced in 2020 to shorten games and made permanent afterwards. It does not apply in the postseason.
Why it is done, and when it is wrong. It changed extra-inning strategy completely: bunting the runner to third with nobody out becomes defensible, because a single run wins it and run expectancy is not the point when the game ends the moment you score.
Batter's Eye: look up anything in baseball