A PASSIONATE Brendon Bolton refuses to put a timeframe on when Carlton's rebuild will be complete but is hell-bent on his club not falling "off the cliff" again. 

The Blues' 0-3 start has heightened scrutiny on the path they are on under the third-year coach, as well as the catchphrase crutch he sometimes falls back on while discussing their fortunes.

But Bolton, appearing stung into action by recent criticism, spoke more openly on the eve of Carlton's round four clash with North Melbourne in Hobart about the direction his side was going. 

"You can only look at history and look at other clubs, so that's for you guys to go and do the hunting on," he said in response to a question about how far the Blues were from the finals. 

"But what I do know is there has been a club that's stripped it right back and we've gone to the draft. 

"How long that takes – I know a lot of people want me to say it's one year, it's two years, it's three years, and then all there is, is a big story that we haven't got there or we have got there quicker. 

"We're just concentrating on sticking to that plan, growing as a club and, in time, we'll look at the free agency market when … it's the right time for us and we'll look at uncontracted players." 

Bolton and list manager Stephen Silvagni, a club legend, have turned over a whopping 42 players in the search for success since joining forces at the end of the 2015 season. 

The coach placed a strong emphasis on defence last season – a focus that kept Carlton competitive for much of the year – but has loosened the reins in 2018 to promote more offence. 

The Blues have not scored a triple-digit tally in the past 36 games, a period in which they have lost 29 times.

"It was always going to be, in the first few years, going to the draft, so we've got a foundation, because this club doesn't want to fall off the cliff again," Bolton said.

"We want to build and be sustainably strong. The only way you can do that is in the first few years, when you've stripped it right back, is go to the draft.

"That doesn't give our players an out; it just means that we're not deviating."

Bolton said the players and his coaching staff were not "down in the dumps" about their on-field results, and the mood at Ikon Park was "more of determination" rather than being "sombre". 

"I think last week the blue skies of it was we are getting the ball inside 50," he said.

"We've grown by about plus-10 – 55 or 56 inside 50s we're averaging – so there's some growth there, and we're not giving up a considerable amount of inside 50s against in the last two weeks. 

"However, when they do get through, they're scoring, so just some detail in and around our defensive mechanism (needs improvement)."

Bolton hinted that ex-Port Adelaide recruit Cam O'Shea would take over the injured Caleb Marchbank's defensive role for the match-up with star Roos Ben Brown and Jarrad Waite. 

Sam Kerridge and Nick Graham are also in contention for a senior recall after strong VFL form. 

But Bolton restated that key forward Harry McKay, who has battled repeated injuries since being the No.10 draft pick in 2015, was not ready for a call-up.