One of the tricky parts about building a bullpen is that you always need to be looking for a way to improve it. Between the fungibility of relievers and how often pitchers get hurt, it only takes a short time for a dominant unit to become of the worst in the league. Since the Yankees had one of the best bullpens in baseball last year, they probably don’t need to go out and add significant veteran depth.
That said, Brian Cashman would be remiss if he didn’t at least look into some buy-low candidates who might be able to fill in at the back of the bullpen.