In my experience the detoriation came after the change in leadership.
Undoubtedly he came off as clever, but being a harasser means that his achievements were outweighed by the benefits.
"he's a harasser => he must be a parasite on the organization"
because then you end up with
"he's provably an excellent worker and hugely productive => he can't be a harasser, you're mistaken/lying"
Some people are really smart and productive and a credit to their profession and also awful to women and/or minorities, and you'd never know if you didn't witness/experience it.
But if they are awful only to white straight males, they are ok?
Harassment is harassment, stealing someone's work is stealing someone's work, let's keep changing the meaning of words to politicians.