There might have been a reason why he was offered the job to begin with. Some promotions turn out to be demotions. Without any support from the top he failed in December to sort out responsibilities on the new board for AUA. He was a 'lame duck' before he actually took office. He kind of paid back by stepping down last minute.
AUA is one of the most difficult jobs in the LH world right now - success not guaranteed, neither for the CEO nor the company.