Boone Logan's 3.46 ERA and 1.34 WHIP do not seem impressive, especially at $1.2 million, but the reason he is so high on this list is because he is the Yankees' only lefty in the bullpen.
Every major league bullpen needs a lefty but Logan's job is to get out lefties and he just does not.
Logan has a .260 BAA and .789 OPS against left-handed batters, but has a .262 BAA and .673 OPS against right-handed batters. He is just as good, if not better against right-handed batters compared to lefties.
Despite this, if Adrian Gonzalez steps up to the plate and I could choose any Yankee from the bullpen (minus Rivera and Robertson), I want Boone Logan.