The standard of England's cricket has been "exposed" during the Ashes series, according to their assistant coach, Paul Farbrace.

Accepting that England "just haven't been good enough", Farbrace urged all involved to be "brutally honest" in their assessment of the team and suggested that "the planning needs to start in the next couple of days" if England are serious about returning to Australia in four years with a realistic chance of success.

"In many ways the last few days have summed up our trip," Farbrace said. "We just haven't been good enough with the bat to get 450-500.

"We've talked a lot about getting in good positions, about how we've had glimpses or sessions where we've played good cricket. But we haven't been good enough over the course of a day, or an innings, to put Australia under pressure. We're constantly chasing the game."

While Farbrace's damning appraisal of England's Ashes campaign may shock some, his honesty may also come as a welcome surprise. Recent days have seen the likes of Tom Harrison, the ECB chief executive, claim that English cricket is "in extremely good shape," giving a sense of delusional optimism.

But Farbrace swept such nonsense aside. Refusing to hide behind "the positives", he insisted the first step in improving is accepting the scale of the problem.

"A series like this does expose issues in your team," he said. "And we have a choice. You either churn out some positive stuff or we can be honest and admit that there are certain areas that are not good enough. That's every single one of us: players, staff, structures, setup. Everybody needs to look very closely and ask if we have got the right people in the right places, and if we are doing the right things.

"There's no point me sitting here chatting about some niceties like some nice periods of play. Nice periods of play and brief glimpses do not win you Test matches and they certainly don't win you Test series in a place like this.

James Vince ended a disappointing series with another nick behind Getty Images

"If England are serious about coming back here and winning in four years' time, the planning needs to start in the next couple of days. You need to start identifying the type of personnel that you need, character-wise and skill-wise, to come here and win. The honesty and planning for next time has got to start as soon as possible."

Farbrace's words could be interpreted in many ways. Some will see them as a swipe at the underperforming players and others a swipe at underperforming coaches. But it does seem likely that the scale of this defeat - and the manner in which it has laid bare England's poverty in spin and pace bowling - will have repercussions to those charged with developing players in those disciplines. Peter Such, the lead spin coach at the ECB, and Kevin Shine, the lead fast bowling coach, might be especially precariously placed over the next few weeks.

But a couple of players will be sitting uneasily, too. If the aim of the England Test side really is to return to Australia in four years with a realistic chance of winning, several of the senior players - Alastair Cook, who has reached 40 only once in the series, Stuart Broad, who has taken his wickets at a cost of almost 50 apiece, and even James Anderson, who has easily been the pick of their bowlers on this tour - could be eased aside to make way for younger men who will make the trip in 2021-22. Certainly it seems England hope to blood more young, fast bowlers in the coming months, though few candidates are fully fit at present and the squad for the New Zealand tour is set to be named in the next few days.

The only player mentioned by name by Farbrace was James Vince. Vince's frustrating tour ended when he flashed outside off stump - a far from unique experienced - and gifted a catch to slip. It left him averaging 26.88 in the series with just two half-centuries from his first 12 Tests. While he has looked good on several occasions, it is clear the frustration with him within the England camp is growing.

"There's no doubt that James Vince needs to score more runs if he's going to play international cricket for England," Farbrace said. "He knows that.

"Of course 25 isn't an average that any top-order batsman wants. He's shown some decent starts, he's showing some glimpses, and we all think 'crikey, this could be the innings'. But there comes a time when 'this could be the innings' has to stop and he has to score hundreds.

"If he'd got 150 in the first innings at Brisbane rather than getting 83 it might have been a completely different tour. You can't look back like that. The blunt answer is the answer is he knows he has to score more runs if he's going to have a future with England."

Farbrace did have some praise. He credited Dawid Malan for showing that "if you apply yourself you can achieve in international cricket" and Craig Overton for "showing glimpses." Most of all, he praised Joe Root, who he said was "growing into and is going to become a very good captain."

"He'll have learned a lot in this series," Farbrace said. "He will only get better from that experience."

But he insisted he "didn't want to be clutching at straws" and suggested progress could only come if all involved were frank in their assessments of the situation.

"There's an awful lot of other things that we've got to get right," Farbrace said. "Various people are going to have to sit down and look at a lot of things. We're always looking at how we can improve.

"But the key is how honest you are with the conversations you have. Sometimes those tough conversations have to be brutally honest."