North Melbourne has not lost faith in the game plan that has made it one of this season's biggest surprise packets, but coach Brad Scott has labeled his team's recent execution of the defensive elements of that plan "horrific".

North suffered its biggest loss of the season at the hands of Collingwood losing by 66 points at the MCG on Saturday.

Scott said his players had received their "right whack" from North's coaching staff after a performance he described as a really bad day.

The Roos coach identified Collingwood's pressure as the decisive factor in the game, with the Magpies winning the tackle count by a whopping 82-46.

Scott believed his team had the "intent" to tackle but labelled their technique "horrendous".

Saturday's loss was North's third from its past four games. After round 14, the Roos sat eighth on the ladder, but they slid to 10th after Saturday's loss while their percentage plummeted from 114.16 at the start of the round to 108.0.

In what shapes as one of the tightest finals races of recent times, the Roos' form slump could prove costly.

Scott, however, is not panicking.

"The overriding thing for me is we haven't lost any faith in what we've done so far this season," Scott said.

"Even the games we've lost this year I've been really proud of the effort and really proud for the most part of the execution of what we're trying to do.

"Today was just a really bad day, a really bad day."

One of the most impressive parts of North's first half of the season was its stingy defence.

But after conceding 100 points or more just twice over the opening 14 rounds, it has done so three times in its past four games. In that stretch, it also conceded 125 points to Essendon, the second highest score it has conceded in 2018.

"I don't think too much has changed in terms of the way we want to go about it, but the execution of it has just been horrific," Scott said of North's defence.

"This is not just the six defenders, this is right across the ground. We just didn't defend anywhere near to the standard that we've come to expect.

"Are the players a little bit tired? Well if you're tired let me know, we'll bring some guys in who are fresh.

"Is it our intent or urgency? I don't think it's that in a massive quantity, but I do think there's a certain element of it that just this much at that level (can hurt you). And defenders who think that they can just sit off a little bit against really good opposition they get exposed.

"We just haven't been the defensive team that we've wanted to be over the last couple of weeks."