Over the last few years the Yankees have gotten pretty good at finding useful arms in the mid-to-late rounds of the draft. Some become bonafide studs (17th rounder David Robertson), some become solid contributors (14th rounder David Phelps), some become trade chips (15th rounder Shane Greene), and some provide short-term help (17th rounder Preston Claiborne).
Coming into the 2015 season, the Yankees had a bunch of these mid-to-late round arms either at the Triple-A level or ready for it. They had no shortage of interesting relievers in the upper levels of the minors.