HAWTHORN ruckman Robert Campbell believes an inability to stick to team structures has been the major factor in the Hawks’ 3-4 start to season 2009.

After being humbled by an improving but inexperienced Essendon, the reigning premier is fast losing pace with the league’s elite as struggles to defend its title.

The 25-year-old was left scratching his head in the wake of Friday night’s loss.

“From the outside people would say injuries but it’s definitely not an excuse we like to use,” he said of the mounting injury toll.

“We’ve got structures in place that will hold us in good stead against any opposition and it’s just frustrating at the moment that things aren’t coming together for us.”

Campbell, like his coach Alastair Clarkson, pinpointed the Hawks’ leaky defence as the critical area.

With five of its premiership defenders – Trent Croad, Stephen Gilham, Brent Guerra, Rick Ladson and Clinton Young – missing from Friday night’s side, and vice-captain Luke Hodge severely hampered by an adductor strain, the Hawks leaked 17 goals to a makeshift Essendon forward line.

The Hawks defence ranks bottom four in the competition.

“It’s frustrating because it’s an area of the ground that’s so important,” Campbell, who was thrown down back in the last quarter, said.

“I’ve gone back there a few times, and even though I’ve played over 100 games, I’d only have a handful down back.

So, you can be experienced as you want in playing games, but unless you get the experience of playing on the good forwards, nothing can make up for that.”

The 2008 premiership ruckman said his side struggled to counter the Bombers’ pace, and would need to find some answers before tackling the fleet-footed Fremantle next Friday night.

Another loss could put it two games and significant percentage outside of the eight with more than two-thirds of the season already gone.

“Essendon was very impressive when they get their handballs going and came through the middle of the ground, but we’ve got some things in place that should hold us in good stead against sides like this, we’re just not getting it done.”