On a night North Melbourne honoured their 1977 premiership heroes, the grim reality of just how far the Kangaroos have fallen this season was laid bare, as they were thumped by a Collingwood outfit that is coming home with a wet sail.

The Roos snapped their seven-match losing streak last weekend against Melbourne, but that looks very much the exception after one of the most uninspiring performances by any AFL side in 2017.

It was made that much worse when North's Coleman Medal fancy Ben Brown was carted off Etihad Stadium late in the second quarter after having his head slammed into the ground in a tackle by Collingwood ruckman Brodie Grundy.

The Pies big man will face scrutiny from the match review panel for the incident, which was reminiscent of one at the same venue a week ago, for which Geelong superstar Patrick Dangerfield was suspended.

Grundy pinned Brown's arms as the Roo tried to dispose of the ball on the wing. Brown got rid of the ball as he was being taken to ground, but was not released by Grundy, his head thudding into the turf.

Brown looked to be knocked out as soon as he hit the ground, and it took more than five minutes for him to be stretchered off the arena.

North could also lose Ben Cunnington, with the midfielder likely to be assessed for a head-high bump that left Pies veteran Tyson Goldsack dazed.

The victory means Collingwood have three wins plus a draw against ladder-leaders Adelaide from their last four starts. Whether it is incumbent Nathan Buckley or someone else coaching the Pies next year, there is clearly plenty to work with.

There had been considerable public discussion during the week about the impact Daniel Wells was having at the Magpies, but bar a rousing goal late in the third quarter he had little effect on the match, with a heavily strapped quad a sign he might not have been fully fit against his former side. The Pies didn't need him though, and nor did they miss skipper Scott Pendlebury. Instead Adam Treloar, Taylor Adams and Jordan De Goey ran riot through the midfield after quarter-time.

That's not to say it was a vintage Magpies showing. They were just as culpable as the Roos in an error-riddled first quarter that served to remind you that this was 16th playing 13th. Wells started on the bench but even a player of his class was not immune to turning the ball over, with his first kick going straight to Cunnington - the North fans' boos quickly turning to cheers.

The Pies appeared to have settled the better when Josh Thomas and Alex Fasolo kicked the first two goals of the game, but North remained well within striking distance after Lynden Dunn coughed it up deep in defence, gifting an opportunity to young Roo Declan Mountford, who duly converted.

The Pies did however click into gear in the second term, with their audacious decision making paying off.

Brayden Maynard's run was a highlight, De Goey was again showing his class, and Darcy Moore looked threatening up forward.

The Pies kicked the only three goals of the quarter, not that North didn't have chances. But, remarkably, despite getting the ball over the top of Collingwood's press several times, the Roos repeatedly blew it inside 50, with Shaun Higgins, Cunnington and Shaun Atley all wasteful.

The poor ball use was overshadowed however by the Brown-Grundy incident, followed moments later by a clash between Jack Ziebell and Matt Scharenberg from which the North captain came off worse for wear. Then Levi Greenwood hobbled off with a suspected knee injury, and the injury list was threatening to challenge the goal tally for length.

Just as he did in the first half, Thomas kicked the first goal of the second half as well, and when Tom Phillips put one through from the pocket there was surely no way back for the Roos - who had kicked just one goal in more than a half, and were missing their best forward. Bereft of options, North sent their banged-up skipper to full-forward, where he kicked five goals. All of them however, came well after the game was lost.