In an attempt to rid players of pressure, a relaxed environment has been a cornerstone of McCullum’s England since he took over as Test coach at the start of 2022.
But on this tour, which began with a genuine feeling England could be competitive, England have appeared unserious with questions being raised about their preparation, training methods and an apparent lack of accountability for mistakes made on the field.
Their time playing golf and the amount of drinking on a mid-series trip to Noosa has also come into focus.
ECB chief executive Richard Gould has been in Australia in recent weeks and will have a role in any changes.
“When I took the job on I remember the situation England were in,” McCullum said.
“I felt it was a great opportunity to use the resource, talent, support base and history that sits in English cricket to ensure the Test side, while there are challenges which are hitting the game all around the world with franchise cricket etc, are still able to get the best players possible who can get excited to come on tour.
“Over the last three and a half years with Stokesy and myself, our record is what it is.
“It has certainly improved from what it was. Whether it is at the levels we all want, probably not, but it doesn’t mean we can’t get there.”
McCullum and Stokes won 10 of their first 11 matches in charge, having taken over following a run of one victory in 17 Tests.
Despite that upturn, they have failed to win any of their major series under this regime.
They drew the 2023 home Ashes and last summer’s series against India 2-2, and lost 4-1 in India in 2024.
They lost this series at the earliest opportunity with defeats in the first three Tests.
“I am obviously disappointed with the outcome of the series,” McCullum said. “As coach you have to put your hand up.
“There are things we have got to look at over the next little while. I would love to carry on because I feel we have got steps to take, things to improve on.
“I feel like we have got the makings of a good cricket team. We haven’t lived up to that down here but there are some good years in front in English cricket.”