At the start of pre-season, Ben Rutten used the term 'blue collar' to describe what the Essendon faithful could expect from their side in 2021.

It was all part of an identifiable Bomber brand he wanted to build as the club's new and 33rd senior coach.

"I think for me, [the important thing for] this footy club is about being a really strong blue-collar footy side," Rutten said in November.

"I want us to be disciplined on and off the field. I want us to have a really strong work ethic and I want us to be a dependable footy club - that’s the basis for any high-performing environment or organisation.

"I’d love nothing more than for our supporters and our members to be able to turn up to the footy each week and know what they’re going to get from the Essendon Football Club."

Four games into Rutten's reign, that vision is already coming to fruition.

Despite a 1-3 start to the season, the Bombers, who have been the most inexperienced team on average across the first four rounds (67 games per player), can hang their hats on being one of the competition's hardest-working and best pressure sides.

They rank No.1 in the pressure factor differential after round four, meaning they have been the best at out-pressuring their opponents.

That was on display in last week's three-point defeat to the Swans, who entered the clash as the League's No.1 pressure team but were out-pressured +0.10 on their home deck.

The Bombers brought the heat from the get-go, but most impressive was their intent when the game was on the line and fatigue at its highest.

Their 38 tackles in the final term was the highest of any side in a quarter since Adelaide's opening term against the Western Bulldogs at a rain-sodden Adelaide Oval in round nine, 2018.

They finished with 24 more tackles than Sydney, with Will Snelling cracking double digits (11) and Zach Merrett (nine) the next highest.

It's no surprise both players lead Essendon alongside Andrew McGrath in the pressure stakes after round four.

So what is the pressure factor, and how does Champion Data calculate it?

The metric describes how much heat the ball carrier is under.

There are six different types of pressure - none, set, corralling, closing, chasing and physical.

Each of the types has a pressure point value associated to it, which contributes to pressure points.

Teams are assigned pressure points according to the pressure they apply to opposition disposals (one pressure act per disposal).

The pressure factor is then calculated by multiplying the total pressure points by 100, and dividing that number by total pressure acts.

While it's a tricky stat to understand, one thing that's crystal clear is the Bombers' willingness to roll up the sleeves.

Their two narrow losses have been tough to take, but if the effort continues, the rewards could quickly come for Rutten and his charges in the wins column.