RETIRED St Kilda defender Sean Dempster says it was upsetting his character was questioned in his final weeks as an AFL player.

A knock in the JLT Community Series was the latest in a number of head injuries that forced the 33-year-old into retirement on Thursday, but reports - in the lead-up to that announcement - had alleged the 222-game veteran was unhappy and considering his future after being overlooked for St Kilda's round one team.

A fiercely private Dempster told radio station SEN on Friday it was a disappointing way to end a highly respected career with Sydney and the Saints.

"Being a quiet person that stays away from the media as much as possible, to have your character questioned, for me, was upsetting," Dempster said.

"It was kind of the first time that I was questioned as a person and my character being questioned.

"I found that difficult given it was based on untruths. That was hard."

Dempster rubbished speculation he refused to play in a VFL practice match with Sandringham after missing out on the round one team, but he conceded his form, and the way the Saints handled his absence, could have been better.

Coach Alan Richardson said in the lead-up to round one he was unaware Dempster was struggling with the injury.

"I think the way we handled it wasn't the best. It allowed for a lot of speculation," Dempster said.

"I suppose the club knew where I stood and what I'm like as a (private) person, and thought (my health) wouldn't gain any (media) traction if they just don't talk about it.

"But I guess not talking about it caused more questions.

"I probably wasn't going to be picked for round one anyway, so there was an element of form to it."

Later on Friday morning, Richardson told reporters the Saints match committee had overlooked Dempster for the club's third JLT Community Series game purely on form.

But the Saints coach said he became aware before round one that Dempster had concussion concerns after suffering a head knock in a clash with Port Adelaide's Nathan Krakouer in St Kilda's first JLT game.

Krakouer was reported for rough conduct following the incident and received a one-match suspension, but Dempster was passed fit to play the following week against Carlton.

"Certainly I left Sean out of the team for JLT three and that was based on form. Basically I was dealing with a guy who wasn't quite performing at the level that we needed," Richardson said.

"And thereafter certainly the conversation started to change a bit. I became aware that we were dealing with a player that had some real anxiety around head knocks.

"So they were separate (issues), I think that's important to make that point. It was a non-selection (for JLT round three) based on his ability to be able to execute the role – form. Then after that there was a bit more information that we were given about Sean's concern about his head knocks and being able to live a relatively normal life.

"We certainly can't argue with that. If that's the way Sean feels, then that's reality.

"But if we need to now knock away the fact that we are dealing with a bloke who has given away the game because he didn't get selected, then that is so far from the truth."

Dempster is likely to be eligible for a payout, given his career has been cut short due to injury.