Dr Tulloch had not taken a high-profile role for some time, having been chief medical officer since August 2012.
His departure was announced to staff in April, and he left last month for a job in Canberra.
Staff were said to be confused between his role, and that of patient services medical director Dick Bunton.
Both men were on the executive team, answering to chief executive Carole Heatly.
Contacted yesterday, Mr Bunton said confusion probably arose because he had been the chief medical officer (CMO) of the old Otago board.
Dr Tulloch was the former CMO at the old Southland board.
''What Carole [Heatly] has done is said she will start from scratch and appoint one CMO for the DHB.
''I was never confused about it, but when we put it out to the workers, so to speak, a lot of the feedback we got said there was some confusion between the roles.''
Mr Bunton was waiting to see if his position disappeared in the shake-up.
Deputy CMOs are likely be appointed in Dunedin and Invercargill.
He wanted to see the job description before deciding whether to apply for the big role.
Asked why he had been the public face of the board on clinical matters, Mr Bunton said: ''You're absolutely right; I sometimes get a stick in the back and get pushed out the front''.
Ms Heatly told the Otago Daily Times the role would ''ideally'' be full-time.
Doctors had told her the person should keep doing some clinical work.
In a consultation document for senior staff, Ms Heatly said only the CMO would be on the executive team under her proposed changes.
''I have also talked to a number of [specialists] over the last months and many have told me that the current arrangements are not working for them,'' Ms Heatly told senior staff.
Dr Tulloch, a urologist, had been 0.8 full-time equivalent in the role, which was advertised internally at first.
''If we are unable to make an appointment from that field, then we would go to external advert,'' Ms Heatly said.
The senior doctors' union has been critical of the board for years over a lack of ''clinical engagement'' between senior management - which included Dr Tulloch and Mr Bunton - and doctors.
Association of Salaried Medical Specialists executive director Ian Powell said it was crucial the appointee was the ''sort of person who will have the confidence of senior doctors in both Otago and Southland''.
