Michelle Guthrie’s departure as managing director of the ABC, while a shock, is not surprising.

In the face of sustained pressure from the government and Rupert Murdoch’s News Corp, she has seemed incapable of mounting a sustained and effective response.

And in this environment of hostility, ABC journalists have felt under siege.

As editor-in-chief – which comes with the managing director’s job – Guthrie was unable to give the kind of robust editorial leadership that journalists need if they are to report fearlessly and independently.

It was clear by the middle of this year that whatever qualities Guthrie brought to the job, editorial leadership was not one of them. Thus the ABC was at a crossroads. It had as its managing director and editor-in-chief a person with no journalistic background who had shown scant signs of understanding the impact of the federal government’s relentless bullying on the ABC’s editorial independence.

Read more: Constant attacks on the ABC will come back to haunt the Coalition government

Then in June, Guthrie gave a speech at the Melbourne Press Club in which she said Australians regard the ABC as a great national institution and deeply resent its being used as “a punching bag by narrow political, commercial or ideological interests”.

It was strong but it came late in the day. By then, the weakness in editorial leadership had filtered down the ranks, so that journalists making everyday decisions on news desks were looking over their shoulders.

One first-hand example makes the point. In May, when Barnaby Joyce accepted money – reportedly $150,000 – to go on Channel Nine with his partner Vikki Campion and talk about their affair, the ABC invited me to write a commentary on the ethics involved.

I wrote that by agreeing to take the money, Joyce had called into question his fitness for public office.

This was too strong for the ABC, and the article did not run. I was told that it was a sensitive time for the ABC’s relations with the government. Instead the article was published by The Conversation and then by The Age and an online newspaper, The Mandarin.

It showed the effect of the water-torture approach the government has taken to the ABC, cheered on by News Corp’s The Australian: grizzles about the work of Emma Alberici as economics editor, most of which turned out to be baseless; grievances about Triple J’s changing the date of its Hottest 100 from Australia Day; more grizzles about Yassmin Abdel-Magied’s comments about Anzac Day.

Strong editors do not sit back and let this happen. Unless there are clear and substantial errors of fact, strong editors stand by their journalists and hit back hard and publicly at unwarranted criticism.

Strong editors also stand up for their journalists’ right to express opinions, when those opinions are based on facts that are substantially true.

And they do this personally, not through bureaucratic complaints processes that dilute the authority of the editor’s voice.

There were signs early on in Guthrie’s tenure that she did not grasp the editorial side of the job.

Having given a keynote address at the New News Conference in Melbourne in October 2016, she took questions from the audience. A man asked her about some ABC story or another, to which she replied that she was not responsible for every story that appeared on the ABC. Well, the fact is that the editor-in-chief is indeed responsible for every story that appears. The journalists in the audience were stunned.

Later, when Guthrie showed up at Senate estimates committee hearings, she would take along Alan Sunderland, who is in charge of editorial policies, to answer questions on the ABC’s journalism. This was simply not good enough. Guthrie was the editor-in-chief. She should have taken the questions – and the heat.

This state of affairs revealed a serious structural weakness in the ABC’s editorial leadership under her control. Sunderland had seemingly become de facto editor-in-chief, but without the ultimate authority. He is a Walkley Award-winning journalist with a strong news background, but highly qualified though he is, it is an untenable position.

Looking ahead, unless the ABC can find someone to combine the functions of managing director and editor-in-chief, as Guthrie’s predecessor Mark Scott did, it would be better to split the jobs.

This is the way good media outlets work. The editor-in-chief answers to the board through the managing director. The board and managing director answer to the shareholders – in the ABC’s case, the government.

The editor-in-chief is thus shielded in a way that enables him or her to make news decisions independent of corporate interests. It is called editorial independence and is the cornerstone of good journalism.

Read more: Why the ABC, and the public that trusts it, must stand firm against threats to its editorial independence

When the editor-in-chief is independent, the spirit of independence filters down to that small army of journalists making everyday decisions. They don’t look over their shoulder.

All that matters is that the stories are worth telling, that the reporting is accurate and fair, that commentaries are based on facts, and that stories are treated on the basis of their news value, and not on other considerations.

The ABC has announced that the acting managing director is David Anderson, who is currently Director, Entertainment and Specialist. This covers “broadcast television networks and associated services, radio music networks, podcasts and specialist radio content”.

Although he has nearly 30 years’ experience with the ABC, he has no background in journalism either, so it looks as if Sunderland will just have to soldier on.