Barclay has claimed the most alarming Welsh failings had little to do with skill and everything to do with mindset.
Wales were torn apart in a 48-7 loss at Allianz Stadium, Twickenham, their defence breached seven times as England dominated the collision area and raced into a 29-0 half-time lead.
While much of the post-match focus centred on discipline and structure, Barclay believes the real damage was done earlier and in more basic areas.
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“It appears there's so much to try and fix in a week. And you can't fix everything,” said the BBC TV pundit and former Scarlets skipper regarding Wales' next match against France.
“I think you fix the things that are easiest to fix, and that sounds like the obvious solution.”
For Barclay, that starting point is defence, not tactics or attacking cohesion.
He argued Wales were second-best in intent as well as execution, particularly in the tackle area, where England repeatedly punched through the gain line.
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“Defence is much easier to do than attack. There's less skill. It's more of a mindset and an intent that you have to have,” he said.
Barclay suggested Wales’ defensive struggles reflected choices made by players in the moment rather than a lack of technical ability.
“You're looking at the lack of intent in the tackle and just to get in front of people,” he said.
“And that's a decision you make. And that's not a skill decision.
“That's a mindset decision to make.”
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That absence of physical authority, Barclay believes, fed directly into Wales’ wider problems, including their discipline.
Wales collected four yellow cards and spent large chunks of the match down to 13 players, a familiar theme during their prolonged downturn.
“So I think if I'm them, I'm looking at defense. How do we get in front of people? How do we slow them down? What happens off the back of that is ill discipline,” Barclay said.
“How do you fix your discipline? But it's probably what happens before that that creates all the problems.
“So if I'm Wales, I'm thinking, let's fix our defence. Let's be a hard team to play against. Let's be a hard team to beat. Let's not give away easy wins,” he said.
“And that's what they did against England. They just gave away so much.”
Those criticisms form a stark backdrop to Wales head coach Steve Tandy’s response as his side prepare to host France in Cardiff on Sunday.
Despite the scale of the defeat and a run of 12 consecutive Six Nations losses, Tandy has ruled out sweeping changes.
“There’s going to be nothing knee-jerk around it and ultimately I knew this when we took the job,” Tandy said. “We’re playing one of the best teams in the world and it’s not going to click overnight.
“This is part of experiencing these moments and using them as learning experiences, making sure we adapt for the coming games.”
Tandy acknowledged the frustration of failing to show progress on such a big stage, but stressed belief in the squad and the longer-term project.
“We’ll always look at ourselves in the mirror. We know where we’re at in our journey,” he said.
“But we believe we can accelerate our development and what was most frustrating is that we didn’t do so.
“They’re a great group to work with. They adapt and are putting everything in their power to be where they want to be.”
