England’s preparation for this series was questioned by several former players before the first Test.
The visitors played one warm-up game against England Lions at Lilac Hill, a club ground with vastly different conditions to Perth Stadium, the venue for the series opener.
England’s situation was complicated by a white-ball tour of New Zealand in October, a series Key said he did not want to “write off”.
Although the England management defended their preparation, McCullum has since admitted it was not correct. The ECB have also opened negotiations with Cricket Australia about guaranteeing minimum standards for preparation in future Ashes series.
Key said England asked to warm up at Perth’s historic Waca ground, only to be told it was unavailable.
“In hindsight, it’s very hard to argue that it’s been right,” said Key.
“The answer isn’t yes, I would have gone and played four games against state teams – I don’t think that is possible in this day and age – but we still had to be better with what we did.”
Stokes and McCullum revitalised England’s Test cricket when they took over.
England’s form has stagnated in the past 18 months, although there was still genuine optimism over the prospect of a competitive series in Australia.
Those hopes were raised by a number of injuries to the home side, including captain Pat Cummins, fellow fast bowler Josh Hazlewood, spinner Nathan Lyon and batter Steve Smith.
Instead, Australia have retained the Ashes they have held since 2017-18.
“Sometimes we make stupid decisions as players out there in the middle,” said Key.
“We’ve got to try and equip them to be able to make better decisions when the pressure’s really on.”
Key said there is room in the dressing room for players to challenge the directions given by Stokes and McCullum, and England are not wedded to a style of play.
“One of the problems with the Bazball narrative is me and Brendon, we’ve never spoken about ‘we’ve got to score quick; this pitch is five and over’,” said Key.
“What we’re trying to do is create an environment where people can maximise their potential and then you then pick the style that you want.
“I’m not in the dressing room all the time to know exactly what happens, but there’s been many occasions where you’ve seen players challenge, where the players have driven it.”
