Not sure that Hauenstein is underpaid but he is by far one of if not the smartest network, revenue management, and marketing minds in the industry and has been absolutely central to DL's turnaround.
Generating superior revenue in a cost efficient way has given Halter plenty to work with.
They also are very good at unlocking many core business values that were central to DL and NW -and there were a lot more fundamental business differences that both airlines shared than there were differences that separated them.