One answer (not necessarily the answer) is to ensure that up-leveled calibration conversations are happening and that next-level managers are informed about their people.

It's a delicate balance and, as a director myself, I don't claim to always get it right. But the goal I aim for is: if we have a good manager hiring great people and a mediocre manager hiring mediocre people that we calibrate correctly across those managers rather than claim that one is inflating their rankings.