LEAKY ladder leader North Melbourne has conceded more points this season than tight-fisted bottom of the ladder Carlton.

Despite not losing a game the Shinboners have conceded 412 points in their four wins compared to the winless Blues, who have conceded 403 points in their four losses.

AFL.com.au could not find a time before this week when such a quirk had occurred. 

Not in 2010. Not in 1985. Not in 1964. Not in any random season we chose to examine, although we can't guarantee it has never happened.

What we can confidently write, however, is that you're more likely to see the Loch Ness Monster than see a ladder that looks like the one after round four.

The defensive numbers provide a big tick to first-time Carlton coach Brendon Bolton, who, if truth be known, would probably also like a win soon to accompany the good defensive result.

Blues coach defends off-target target man

The figure shows the Blues are organised and building towards an objective, or as Bolton emphasised on Wednesday morning, they have direction.

Of course the gap between the two clubs at either end of the table widens when points for are examined.

The Blues are second bottom on that measure, just above Essendon and the only team not to have at least one player to have kicked five goals this season.

They also have the worst percentage at 60.55 per cent.

Bolton understands that deficiency better than anyone. He's changed the way the Blues are playing and has made clear the direction he wants his team to head.

His approach is to make winning a by-product of hard work rather than agonising over the win-loss column right now.

North Melbourne is a scoring machine and has seven players who have kicked at least five goals this season.

The Kangaroos have shown their game stands up in finals so only have to tinker (or eliminate costly turnovers) to find a better balance between defence and attack to go better than fourth.

The ladder after round four shows this season is throwing up numbers unsighted for a long time.

Gold Coast has never had more than 400 points-for after four rounds, with 436 points an indication of its improvement.

North Melbourne has not been on top of the ladder since 1998.

The Western Bulldogs have not conceded fewer points in its first four games since 1960 when it conceded 199 points, the year before it played in its most recent Grand Final.

The second placed Bulldogs have let the opposition score just 216 points in four games, a whopping 194 points fewer than top of the ladder North Melbourne.

No club has used 32 players in the first four rounds, as Collingwood has done, since Richmond in 2010.