Have the pitcher roll a die toward each batter and the number showing tells how many bases he gets. A 6 gives him 1 run and he ends up on second. The catcher brings the die back to the pitcher.
The next guy gets a 1 and now there are men on first and third.
The next guy rolls a 4 which scores 3 runs.
That half of the inning is over, since each roll is also worth an out at the end.
No time consuming walks or strikes. No bats. Too dangerous. The infielders and outfielders are witnesses to make sure correct scoring is kept.
No fans allowed since they are too noisy when drunk and they tend to wake up the players. I like baseball, but I can't stand looking at it anymore. It's a great way for a lot of people to waste time. It's better than golf for that.
But I think the pitcher and batter should each roll a 20-sided die and depending on their prior stats and the result of the roll and some complicated set of charts that only D&D folks will understand, the player is either out or advances to the specified base.
Wearing Medieval costumery while playing should be strongly encouraged.