DEAN Laidley has promised to introduce new blood to sort out his side’s “Jekyll and Hyde” tendencies, after North Melbourne squandered a 16-point three-quarter-time lead in going down to St Kilda at Carrara on Saturday night.

A clearly disappointed North Melbourne coach said he wouldn’t spare the axe in finding a mix of players that is competitive week-in, week-out.

The Roos lost to Fremantle by 53 points in round 12, but bounced back to surprise Hawthorn by 27 points last week, before being beaten by the Saints.

"It’s really disappointing for us and really disappointing for the supporters that the team can play so well one week and then can’t perform the next,” Laidley said.

"It’s the break now and time to assess guys who are consistently inconsistent – not so much the young guys, who we have got to keep playing, but the guys who have been around for a while.

"We’re going to have a look at Todd Goldstein and give Ben Ross some time.

"It’s Jekyll and Hyde (at the moment) and we can’t stand for that. We have to make changes and we certainly will.”

While Laidley was unwilling to single out players whose spots in the team were under pressure, his assessment of the last quarter fadeout against St Kilda suggests midfield changes are likely.

The Roos had the better of the opening exchanges and kicked the game’s first five goals.

"Have a look at (St Kilda’s) possession rate in the midfield in the last quarter compared to ours – it’s pretty simple,” he said.

”I think in the first 20 minutes of that last quarter it was about 30 possessions to 68. Our midfield didn’t win football.

"We can’t rely on Adam Simpson being as brave as he was. We need his understudies to be consistent and they are not.

"We talk about mental toughness being the ability to react at pivotal moments but some guys can’t do that.”

Laidley refused to use his team’s heavy travel burden – North Melbourne has been on the road five times in the last eight weeks – as an excuse for the result.

The coach himself will be on a plane again next weekend, scouting the Sydney Swans’ clash with Collingwood in Sydney.

He could only identify a single positive from the Saturday night’s defeat.

"(The players) get four or five days off now – that’s it," Laidley said