https://www.mlb.com/news/mlb-playoff-tiebreaker-rules
Three Clubs Do Not Have Identical Records Against One Another
• If Club 1 has a better record against Clubs 2 and 3, and Club 2 has a better record against Club 3, then Club 1 chooses its designation, followed by Club 2.
• If Club 1 has a better record against Clubs 2 and 3, and Club 2 and 3 have identical records against one another, then Club 1 chooses its designation. Clubs 2 and 3 would follow the two-Club tiebreak rules to break their tie to pick the next designation.
• If Club 1 and 2 have identical records against one another, but each has a better record against Club 3, then Clubs 1 and 2 would follow the two-Club tiebreak rules to break their tie to pick the first designation.
• If Club 1 has a better record against Club 2, Club 2 has a better record against Club 3, and Club 3 has a better record against Club 1; OR Club 1 has a better record against Club 2, Club 2 and 3 have identical records against one another and Club 3 has a better record against Club 1; OR Club 1 and 2 have identical records against one another, Club 1 has a better record against Club 3 and Club 2 and 3 have identical records against one another, then:
a. The Clubs will be ranked by their overall winning percentage amongst the other Clubs combined. The Club with the highest overall winning percentage in that group chooses its designation, followed by the team with the next highest overall winning percentage.
b. If two of the Clubs have identical winning percentages, then they would follow the two-Club tiebreak rules to break their tie to pick their designation.
c. If all three teams have identical winning percentages, then the tiebreak rules above (No. 1) for three clubs having identical records against one another should be followed.