Ranking under-25 players who could impact MLB postseason

I typically update my ranking of the top MLB players under age 25 once a year, but with playoff rosters loaded with young talent, the past two seasons I've produced a special, shorter edition (2018 | 2017) highlighting the top young players on postseason teams. And I'm doing so again for another youth-infused postseason field.

I use seasonal ages here, so to be included, a player had to be 24 or younger on July 1.