Here are the possibilities:
Sox go 0-3, 2 behind NY
Sox go 1-2, Dead tie for AL East, NY with 4 more games yet to play , probably worth 1 to 1 1/2 game gain.
Sox go 2-1, NY would be 2 up , Yankee's 4 games to play can only tie at best
Sox sweep'em at 3-0. NY 4 back and the 4 games don't close the gap.
Note---there is no way for the Sox to be 3 up after Sunday.
Conclusion, a sweep is the most effective way of flushing the Yankees into the Bronx sewer system. It would be epic.