From the start of 2015 until last weekend's defeat to Geelong, the Bulldogs have played without Boyd eight times and lost all eight matches. That's right - the reigning premiers haven't won a game without him in almost two-and-a-half seasons.

Since Luke Beveridge took over as coach heading into the 2015 campaign, the Dogs have been beaten 20 times. That eight have been without Boyd in the line-up (including the narrow loss to Greater Western Sydney in round six) shows how important his leadership, smarts and toughness have been in the rise of the Dogs.

There have been several reasons for their spluttering start to the season, with Tom Liberatore the latest to have his fitness and thirst for the contest questioned. But it's clear Boyd, at age 34, remains a vital cog.

He was rested against the Giants in Canberra and sat out the Simonds Stadium clash with a shoulder issue.

Statistics don't always tell the full story, but Boyd's absence is felt in two ways.

"He has gone to half-back and he is one of the fittest in endurance the Dogs have got on their list," a Dogs insider said.

"He has this ability to get from contest to contest, which some half-backers don't have. That's what they miss when he is not playing - that ability to get back and help, especially when the ball hits the ground."

Boyd wasn't known for his pinpoint kicking in his days as a specialist, tough-as-teak midfielder but that has changed since a shift to half-back under Beveridge.

"His kicking efficiency over 15 to 35 metres, he rarely misses when it comes to that. That's why they love him back there now, and that's why he has been so successful, because when he gets the ball in hand, he doesn't miss," the Dogs insider said.

"Therefore, they start their transition effectively and he is not afraid to hit that one [teammate] back in the corridor.

"They are probably the main two things where Boydy has been able to keep his consistency. They miss that when he is not playing. Caleb Daniel tried to fill that [role] last week a bit."

Boyd is one of a handful of players clubs have struggled to succeed without since the start of 2015.

Swans defender Dane Rampe returned to line up against St Kilda on Saturday for the first time since he broke his arm in a freak training accident, and his impact was immediately felt. The Swans had been 2-5 without him since the start of 2015.

Last year's grand final is one of the few matches the Swans have lost with Rampe. Photo: Scott Barbour

"He is a very good player and very adaptable so can play on tall and smalls. He has great voice and an ability to get the defence organised," a Swans insider said.

Equally, Nick Riewoldt remains a barometer for St Kilda. The former captain has been restricted by a knee that he hyper-extended against Melbourne in round one. His lateral movement has been an issue, although he remains a potent threat inside attacking 50.

There have been calls for the Saints to rest Riewoldt but statistics explain why they may be loathe to do so. Since the start of 2015, the Saints have won only one of the seven games for which he has been sidelined.

Statistics say resting Riewoldt does not profit the Saints. Photo: Getty Images

Ben Brown may be regarded as North Melbourne's key forward of the next five years but the impact of Jarrad Waite cannot be ignored. Like Riewoldt, he is a savvy veteran in terms of winning a contest and is hard for teammates to ignore when leading at the ball.

The former Blue crossed to North as an unrestricted free agent in 2014. The Roos are a staggering 2-15 when he is absent. No wonder those lengthy periods on the sidelines, through suspension or injury, are such a source of frustration.

Aaron Sandilands' ability to give fir st use of the ball to a teammate has been pivotal to Fremantle in the ruck, highlighted by the Dockers being 3-15 without him. It's when he grabs telling marks around the ground that he becomes an almost unstoppable force.

That the Brisbane Lions have been 0-22 without promising rebounding defender Tom Cutler, the Gold Coast Suns 0-11 without key defender Steven May and Carlton 1-10 without ruckman Matthew Kreuzer probably says more about the overall weakness of their teams in the past three years than the impact of their absences.