Red Sox record: 86-58 (18 games left)
LAA record: 86-59 (17 games left)
Tex record: 80-65 (17 games left)
If the Sox win 11 more games, they have 97 wins. If Texas wins out, they have 97 wins, but in the process beat the Angels 7 times, meaning the best possible record from here on out is 10-7, meaning they can only win 96 games. Sox win the WC.
If the Angels win out, the same is true, but the Sox win the WC against Texas and not LAA.