In a “full season,” the answer is: 1989-1992. (Actually, that was a five year run from 1988-1992. And, that 1989-1991 team was one of the worst in Yankees history.)
Of course, with 87 wins or less in 2016, the new answer would be 2013-2016.
If that happens, let’s please be sure to get that on Cashman’s Monument Park plaque.