Coach Michael Voss has said Carlton let themselves down against GWS as his charges lick their wounds from the surprise upset loss.
The second-placed Blues were on a five-game winning streak ahead of Saturday night's game and kicked away to a 39-point lead late in a scintillating first quarter.
But the Giants pulled off a huge comeback, then held on amid a late Blues surge for a 18.8 (116) to 16.8 (104) win at Engie Stadium, leaving Voss bitterly disappointed.
"The competition is extremely even," Voss said.
"We knew coming up here what sort of challenge GWS would be. They're a good footy team, and we were playing on their home venue. So it was always going to be a challenge.
"But we're trying to be able to become a very, very consistent football team and that's what we're still trying to achieve.
"I feel like we've got, I guess, some confidence from the public that we can perform, and we can perform when we need to.
"But we let ourselves down today, we absolutely let ourselves down."
Voss indicated the Blues had lost their focus after setting up their early lead, allowing the Giants back into the contest
"I mean in some ways, you could argue that the scoreboard shifted where our focus was," he said.
"We, over a long period of time now, have a great clarity on and a feel for when things work for us and when things don't and we've spent a hell of a lot of time on what our identity looks like, and we've got enough experience to know what we want to value and what's really important to us.
"And the reality is that we drifted away from that."
Jesse Hogan booted five goals for GWS and Voss indicated a lack of midfield pressure had left his defence in strife, with the Giants able to score heavily from stoppages.
"It's not often we concede 70 points from stoppage - like that is an enormous number," he said.
"So that's clearly something we've got to look at.
"It's not too often we look at a scoreboard where we concede 100 points like that, and when you're getting that sort of clean ball through, and your defenders are left one-on-one, and we can't get the support.
"We've been really good at being able to support one another and I felt like we probably let our defenders down a little bit."
Jacob Weitering (corked quad) battled through the game but Voss expected the gun defender to pull up fine.
The Blues next face the Western Bulldogs at Marvel Stadium next Saturday, while GWS face Richmond at the MCG on Sunday.
