In 2024, Geelong struck a secret agreement with Kolodjashnij, who on Friday evening identified himself as the player in question, whereby he took on legal responsibility for future brain trauma in a bid to exonerate the club and its medical staff from court action down the line.
The bombshell concussion case emerged on Thursday and pressure mounted on the league and Geelong after the AFL didn't hand down any punishment that night.
On Friday afternoon, Geelong chief executive Steve Hocking said he had signed off on the deal and confirmed the "please explain" notice.
"I take responsibility for the fact that we didn't lodge it with the AFL and the (AFL)PA," Hocking told reporters in Geelong.
"... I have received a letter of please explain from the AFL in relation to this matter, so we'll deal with that over the coming days."
Hocking said not registering the deal was a "mis-step" and was uncertain what consequences Geelong would face.
"We've got a please explain letter, and at the appropriate time we'll work through that with the AFL," he said.
"We'll have to respond to that, and then it'll be up to the AFL, and whatever that is, we'll accept."
Later on Friday, Kolodjashnij issued a statement through Geelong, confirming he was the previously unnamed player.
"While I appreciate the efforts made not to identify me, the speculation has left me feeling I needed to address this personally," Kolodjashnij said.
"I participated fully in the AFL's independent concussion panel process, respected its independence, and was comfortable with the outcome. I have continued playing AFL football since.
"What disappoints me most is that my private medical information has been made public. Everyone deserves the right to keep their confidential medical information private.
"... I am healthy, feeling good, and focused on playing my role for the team for the remainder of the season."
The 2022 premiership defender, 30, has played 209 games.
Kolodjashnij's twin brother Kade, who played for Gold Coast and Melbourne, retired prematurely in 2020 due to concussion.
On Thursday night, calling it a "complex and unique case", the AFL had insisted it was "satisfied that the letter was not used by Geelong to allow a medically unfit player to return to play".
Geelong also issued a statement, saying they would remove the waiver from the contract.
"The club was not attempting to vary the terms of the AFL standard playing contract, or attempting to avoid its responsibilities under health and safety laws," the Geelong statement read.
New AFL Commission chair Craig Drummond was the president of the Geelong board when the deal was struck.
Drummond was not mentioned in the AFL statement.
Drummond didn't front the media and issued a three-line statement on Thursday night calling concussion a "challenging medical and legal issue for all contact sports globally".
Multiple AFL players, including former Melbourne star Angus Brayshaw, champion West Coast defender Jeremy McGovern and former No.1 pick Paddy McCartin, were forced into retirement due to repeated concussions.
Several deceased players, including Danny Frawley, Shane Tuck and Graham 'Polly' Farmer, were posthumously diagnosed with degenerative brain disease Chronic Traumatic Encephalopathy (CTE).
There is also a multimillion-dollar concussion class action against the AFL, led by former Geelong defender Max Rooke, in the Supreme Court of Victoria that is set to go to trial next year.
