Exposed: Carlton's backline was its biggest problem during the match against Essendon.

Exposed: Carlton's backline was its biggest problem during the match against Essendon. Photo: Sebastian Costanzo

TONIGHT we'll learn a little bit more when the embarrassed Blues take on the confident Dockers in Perth.

A week ago, the Blues were cock-a-hoop. They were premiership favourites after monstering the Magpies. But their weak capitulation to Essendon put an end to that.

The Dockers, on the other hand, came to Melbourne and had a rare win. For years, Fremantle has been OK at home and woeful on the road. Now, under Ross Lyon, they have a new mantra: to win anywhere, against anyone, any time. The days of mollycoddling in the purple haze camp are over.

Brett Ratten had a bad day in the dugout last week. That happens. But he will need to get it right tonight. Time to forget playing Michael Jamison up forward. He is strictly a defender - and an out-of-form, not fully fit one at the moment. Ruckmen Matthew Kreuzer and Shaun Hampson must change more at full-forward and not via the bench. For most of the first half last week, there was no tall kick-to option deep in the forward line. It meant Eddie Betts had nobody to crumb to and, as such, he had just one touch in the first half.

Mitch Robinson needs a specific lockdown role. Last week, he started on Dustin Fletcher, but it didn't last long, so then he freewheeled in midfield. It's no good when he tries to play beyond his capabilities and continually kicks the ball to the opposition.

Chris Judd was hounded relentlessly by Heath Hocking. So did any Blue go out of his way to hammer Hocking? No. Essendon's fierce resolve was evident early when Sam Lonergan put Andrew Carrazzo out of the game. The Blues weren't switched on.

A Carlton premiership coach told me he was concerned when he compared the two teams' on-ground warm-up: Essendon was aggressive, Carlton passive.

The biggest problem exposed on the day was Carlton's back line. None of Lachie Henderson, Nick Duigan, Chris Yarran, Zac Tuohy and Paul Bower are experienced, hard-nosed defenders. They rely on one another, so if one mucks up, there's a mate nearby to cover. The Bombers wouldn't allow that. The Essendon forwards took their opponents up field and spread them wide.

Often, inside the Essendon forward 50, there was nothing but space. Time and again Carlton defenders were turned inside out as the Essendon forwards, led by Stuart Crameri, Alwyn Davey and Leroy Jetta, ran into wide openings. They continually won the one-on-ones with speed and desire.

Dockers coach Lyon would have taken note and is likely to employ similar tactics. To protect his backmen, Ratten has a decision to make. Does he drop Bryce Gibbs into defence or play him midfield in Carrazzo's absence?

In a perfect world, Gibbs would play as a midfielder and would be one of the game's elite players, just as Marc Murphy has become. But the Blues haven't been able to do that. For the sake of the team, Gibbs has had to play in the back line as his skills have been desperately needed there. The 23-year-old reads the game to perfection, can take contested marks, spoils effectively, intercepts and rarely misses the target by foot. Last year, he was the competition's top link player and No. 2 for effective foot disposal. So he just has to play in defence to help out the inexperienced back-line boys.

That being the case, Lyon will have plans in place to quell his influence.

The new coach's influence on the Dockers is already evident. Being able to defend, win contested ball, give repeat efforts and a preparedness to sacrifice for the good of the team are non-negotiables.

For the Dockers to succeed in 2012, it was vital that their two most influential players buy into Lyon's plans. Despite the accolades that have come the way of Matthew Pavlich and Aaron Sandilands, neither has much in the way of September highlights. Pavlich has cut his skinfold count and returned to a key forward spot where he is most dangerous.

And Sandilands - ruled out tonight after hyper-extending a knee last round - has to change his ways, too. The giant ruckman dominates hitouts, but far too many are ineffective. He needs to develop his palming and get a better understanding with the men who feed off him.

Don't be surprised if Lyon uses Zac Clarke more in the ruck. He has just 25 senior games but the kid could be anything. At 203 centimetres, he runs like the wind, is athletic and fast becoming what the game is about.

Last year, the Blues beat a down-and-out Dockers outfit in Perth. A win tonight would be much more meritorious. But I don't think that will happen. Last Friday when the Dockers beat the Saints, I saw a resolve that has rarely been seen from a Fremantle side.