"It's when you go and look really closely and encourage people to dig around in their experiences that they haven't enjoyed so much at work, you find some things that you don't like the sound of," he told Radio NZ.
"And that was certainly the case here - favouritism, exclusion, abruptness, unreasonableness. None of these things are the sorts of things you want in your workplace. So we're really keen to work with staff to go forward from there.
"We're not satisfied with a workplace that people are not fully happy and engaged and productive in."
He said he believed many of the complaints were historical.
"I don't think things have got worse in this department at all. If anything, the staff who have only been in DPMC a shorter period of time didn't have the memories of some of the negative behaviours that staff who might have been here a longer period of time - or in our predecessor agencies - were highlighting."