With Mattner retired, the Swans are now desperate for the quick return of Rhyce Shaw
That is the opinion of Craig Bolton, a two-time All Australian who won a flag with the Swans back in 2005.
Mattner's retirement on Thursday due to chronic hip problems leaves another gaping hole in a defensive line that was the AFL's best in 2012.
Alex Johnson (knee) is already out for the season, while Lewis Roberts-Thomson (knee) and Shaw are at least a month away from a return.
Shaw was first diagnosed with an abdominal tear in round two and hasn't been sighted since, with associated groin and pelvis issues meaning there are significant question marks surrounding his return.
"We’re really not quite sure when he’ll be back training," Swans physio Matt Cameron admitted this week.
And that spells trouble, according to Bolton.
"There's a big hole," Bolton told AFL.com.au.
"I think Marty not being there the last little bit, and Rhyce Shaw, they really need that run and carry.
"They're a much more dangerous side when they're not just relying on Nick Malceski.
"(Shaw) is critical. When you've got him and (Malceski) there, and it was the same when Tadhg Kennelly was playing and Marty, it becomes very hard for the opposition to stop.
"Obviously with the absence of Marty now, it's important they get Rhyce back fit and firing as soon as possible."
The Swans have coped well thus far, with rookie Dane Rampe proving a pleasant surprise filling a similar role to Johnson.
Co-captain Jarrad McVeigh, who started the year in devastating form in the midfield, has also reverted to a defensive role.
But Bolton, who knows first-hand what it's like to have a career ended prematurely by injury, believes Shaw is indispensible.
Bolton spent most of the 2010 season trying to overcome an Achilles problem before snapping a tendon in his ankle on the eve of the 2011 campaign.
Facing another year on the sideline, he announced his retirement, leaving him stuck on 199 career games.
"It's tough," he said. "I spent the last year of my career trying to get back.
"All you're worried about is that next game and tryingto get back to that form you can have and I'm sure Marty's been through that same frustration over the last month.
"To his credit he's been able to play at a pretty goodlevel, albeit in a lot of pain I would imagine."
Bolton, who started his career with the Brisbane Lions, believes Mattner was crucial to the Swans being able to alter their playingstyle.
"He was obviously one of the recycled players that Sydney have had so much success with over the years," Bolton said.
"He gave the team something we lacked, that run from the backline.
"We were always known as a defensive, dour side, but he was one of the players who started to change that mould.
"He became one of the great defenders in his ability to defend and also to run off and attack, which is so important these days."
James Dampney is a reporter for AFL.com.au. Follow him on Twitter: @AFL_JD