The Bulldogs were within three points of North Melbourne 10 minutes into the fourth quarter, but lost by 29 points as the Kangaroos kicked the last four goals of the game.
To that point McCartney's side had held its own but was overrun in the final 15 minutes, which left the third-year coach disappointed post-game.
"They hung in there for longer than us and stuck at it," McCartney said.
"They've been through a lot of games like this themselves the last 18-24 months that we've all watched and that they've talked about incessantly, and they hung in there a bit better than us."
The Bulldogs, on the back of a road trip to Perth last week in stifling conditions, kept the game on level terms until the later moments, when several key North players, including veteran Brent Harvey, stood up.
"That's what 'hanging in there' is and that is what the strong, hardened teams do. And they all know that they're going to do it, they rely on each other to do it and they rarely let each other down," he said.
"And that's what a footy program is designed to build. We're well and truly down the path with it. It would have been real interesting if the game had stayed level for another 12-15 minutes tonight. What would have happened?
"That's our challenge. They were better at it when it really mattered than us, so we've got to butter up and give ourselves a chance to be in the game next week, and take it when it's there."
All Australian pair Will Minson and Ryan Griffen (in his first game after an interrupted pre-season) were among a group of Bulldogs down on regular output, with another young star, Tom Liberatore, one to feel the effects of last week's heat.
The Dogs were also forced to use running half-back Easton Wood as a key defender against the Roos' triple tall threat of Daniel Currie, Drew Petrie and Aaron Black.
But McCartney said while the Bulldogs lost some of Wood's drive, other options in the VFL were not standing up.
"If people really deserved a game, they'd be out there. And we could play some people, who aren't playing the way we want in the VFL, and they'll serve it up at AFL," McCartney said.
"Easton Wood might actually be growing up in front of our eyes because we've put more on his plate, too, that he's having to deal with a taller opponent. We think we've got a pretty good defender in the making there."
Following the Bulldogs' round-one defeat to West Coast at Patersons Stadium last week, McCartney said patches of the game annoyed him.
But he has belief in the club's program, and expects improvement next week against Richmond at Etihad Stadium.
"I do sometimes get a bit frustrated - we all do. That's what management is; you want things to be really good and at their best so you do get frustrated when it's not there," McCartney said.
"You look at yourself and go 'Am I telling them the right things? Are we creating the right drills?' But they're drills that I've seen work for a long time with young people, older people, and they actually build good teams.
"I'm a bit cranky right now but I'll get over that."