SS
Shortstop.

The sixth position in baseball between second and third base.

1 - Pitcher, 2 - Catcher, 3 - First Base, 4 - Second base, 5 -  Third Base, 6 - Shortstop, 7 - Left Field, 8- Center Field, 9 - Right Field.
The Yankee's best SS right now is playing third base.