A team has finished a game with 20 left on base 129 times since 1897, most recently Boston Red Sox on 10 April 2015. That is about one every 3,434 team-games.
Box score for the most recent one ↗
14 15 16 17 18 19 20 21 22 23 24 25 26
The whole distribution — Runners Left on Base · All 18 shapes