"I think the forwards' job is to fill the salary cap, and they're doing a good job doing that," Richards quipped. "We're happy down back and doing our thing."

And it's a thing the pair, who are so close off the field that Richards once tagged along as a "third wheel" for a weekend away with Grundy and his wife, have done well since 2011.

Considering they are arguably the best defensive pairing in the league, it may seem hard to comprehend there was a time when Sydney's defence was viewed as an Achilles heel rather than a strength – a critique which irked Richards.

"I can remember going into 2011, Craig Bolton had retired and Leo [Barry] maybe the year before. There were huge question marks," Richards said.

"They thought we had a good forward line and a good midfield but they had huge question marks on our defence. A lot of people at the start of pre-season thought that was a real weakness.

"I was internally pretty annoyed with that because I thought we, as a defensive unit, could be a force for the team."

Richards' prediction has proven correct. When the Swans won the 2012 premiership, they boasted the most miserly back six in the competition. This year, they are second to Fremantle although not much separates the two defences.

Richards said he drew inspiration from Matthew Scarlett and Tom Harley and wanted to be part of a defensive partnership comparable to the back-line generals from the great Geelong teams of 2007-09.

"They were the two for me who I looked at," Richards said. "If we were going to be a good defensive unit, I looked at those two Geelong defenders and thought 'we can try and emulate that because they operated so well together'," Richards said.

"They just got the job done every week."

Grundy had a different appreciation of their effectiveness, having seen first hand what life was like playing on Harley in his old role as a forward for the Swans.

"Their defence was so sound, you knew what the best was so you had to keep working towards that," Grundy said.

Since Richards resurrected his career in late 2010, he and Grundy have played 94 out of a possible 99 games together. Continuity has been a key factor in their on-field relationship, they say.

They understand each other's strengths and weaknesses. For example, Grundy knows Richards is an excellent reader of play who does not need to initiate contact with his opponent, while Richards acknowledges Grundy has the bulk to hold his own in one-on-one duels.

And they have close to a sixth sense of each other's presence.

"There's plenty of times when I know, without a loud voice, Reg is in the area so I can body up an opponent and he can come over the top and vice versa," Richards said.

Grundy said: "It's hard to explain. I think it just comes back to playing with each other a lot and knowing what each other's good at. When Teddy's out of position, I always try and help him and the same with me."

The pair also give feedback during games, sometimes instructional – like giving tips on how to use their body or improving on-field communication – though not always.

"Sometimes we get together and have a whinge about what the mids are doing, and that's quite common," Richards joked. "There's plenty of room for banter on the field as well."

Off the field they are close. Grundy has planned his post-season holiday to Europe with his wife so he can fit in Richards' bucks party. And Richards tagged along with Grundy and his wife for a weekend away to Hamilton Island in 2011 for Tadhg Kennelly's wedding.

"I was a third wheel going on the scuba diving tours on the Great Barrier Reef," Richards said. "I kept on asking 'are you sure it's all right?', and they said it was fine."