Sydney have changed their minds and will appeal against the severity of Luke Parker's six-game VFL ban.

Veteran midfielder Parker was handed a six-week ban for a heavy bump in a VFL game that hospitalised opponent Josh Smith.

Sydney pleaded guilty, arguing instead during Tuesday night's lengthy hearing against the severity of his penalty.

But on Wednesday afternoon, the Swans decided to contest the verdict.

Parker has not played any AFL football for the Swans this season and the suspension means he will not break back into their senior team until well into July, at the earliest.

The VFL could have suspended him for four games but referred Parker directly to the tribunal for the incident last Friday night while he was playing for the Swans' reserves side against the Frankston Dolphins.

In handing down the penalty, tribunal chairman Tim Bourke said Parker had failed in his duty of care to Smith.

"We weigh up the matters … the incident being off the ball, unforeseen by Smith, causing injuries likely to result in surgery and 10 weeks missed games by Smith," Bourke said.

"[It] brings the tribunal to the conclusion this was not at the lower end of carelessness.

"It's the totality of the incident which ultimately settles the sanction to be imposed by the tribunal."

Smith was hospitalised after Parker ran past the ball and the incident was graded as careless conduct, severe impact and high contact.

Swans advocate Nick Kidd used GPS data to argue Parker was barely at walking speed when he bumped Smith, to block him from the next contest.

Kidd also argued that given Parker had only been suspended once previously in his lengthy AFL career, that warranted a discount on this ban.

But Bourke said Parker had "some nine sanctions", adding: "We find he's not a player that qualifies as a verifiable example of exemplary disciplinary history."

Kidd used a series of still images from the video footage to contend Smith's injuries were from an accidental clash of heads, immediately after Parker had bumped him.

The medical report said Smith had a concussion and facial fractures, plus he would need surgery. He is expected to be sidelined for 10 weeks.

In his evidence, Parker said he had contacted Smith to apologise and check on his welfare.

"It was no intention of mine to make contact with his head," Parker said.

But VFL advocate Morgan McLay argued Parker had breached his duty of care to Smith in the incident and deserved the six-week ban.

"There's a clear need to protect the head. Everyone's worst fears have occurred," McLay said of the injuries to Smith.

Parker had been unable to return to the Sydney AFL side since recovering from injury a month ago.

He has played 283 senior games for the Swans and received support earlier on Tuesday from coach John Longmire.

"If you look at it really closely, he went to block a player and shepherd a player that was coming through and got it wrong," Longmire said.

"He went to block and he actually wasn't moving, he was stationary at the point of contact. He didn't go high, unfortunately, it didn't work out the way that he intended it to do."

AAP