NOT THAT Alastair Clarkson ever needs an invitation to be the loudest and most opinionated voice in any room, but he was provided one last Thursday morning when the game's senior coaches dialled in to a video conference with the AFL's CEO and football department boss.

With three winners of the past five premierships absent for the meeting, Clarkson had status as the most recent flag winner, and proceeded to launch into his usual rant about not being adequately listened to by headquarters.

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Damien Hardwick and Luke Beveridge were surprise scratchings for the gathering. Adam Simpson and Justin Longmuir were understandable ones, given it was 5am in their part of the world.

Clarkson then went hard about rotations within a match (capped at 75 in 2021, down from 90 in 2020) and also became the most dominant voice when the topic of a substitute player being added to teams was raised.

Six days later, and just 32 hours before the start of the 2021 AFL home-and-away season, AFL CEO Gillon McLachlan and football department head Steve Hocking announced clubs would get to use a 23rd player in each match as a replacement for an injured or concussed teammate.

The new rule has been introduced as part of significant adherence to health and safety of footballers, particularly concussion. But like so many protocols in the AFL system, there is sufficient ambiguity for this rule to be manipulated.

Incidents which involve a player being concussed will see that player removed from the match and unable to play again for a minimum 12 days. Had the AFL restricted use of the substitute player for concussion incidents only, then it would have been much easier on the medicos.

For incidents that don’t involve concussion, there will be wiggle room in how clubs determine the unavailability of a player within a game, and arguably even more in how clubs seek to have certain subbed-out players available for selection the following week.

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The AFL has been very careful with its wording around the application and policing of this rule change.

"A medical substitute can be activated immediately after it is determined a player is medically unfit to continue to participate in the match and, due to the nature of the injury sustained, it is reasonably determined the player will be medically unfit to participate in any match for at least the next 12 days," said the AFL on Wednesday.

Note the use of "reasonably determined". There's the wiggle room. A player may have taken a pre-existing injury into a match, isn't performing well on the day, and hey, there's a fresh player sitting on the bench making that pre-existing problem look mightily like a match-ending one.

Likewise, it may be "reasonably determined" that a player is injured sufficiently enough in a match to be medically subbed out, but equally "reasonably determined" to be of adequate fitness to play the following week.

Clubs are always more than reasonably determined, regularly obsessed even, to find loopholes in any rules, and before the game's medical fraternity takes its preferred position on the high horse, let's not forget that even in recent times players badly concussed in a match were sent back into battle.

"Only the club medical officer can determine a player is medically unfit," said the AFL on Wednesday.

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Also: "On or before the first working day after the match, the club medical officer must provide a medical certificate to the AFL certifying that the player replaced by the medical substitute player sustained the injury."

And: " A club that is found to be in breach of the regulations relating to the medical substitute is subject to sanction under the AFL Rules, including, for serious transgressions, for a breach of AFL Rule 2.3 (being the prohibition on conduct unbecoming or prejudicial to the interests or reputation of the AFL or to bring the game of football into disrepute)."

The experiences of dealing with COVID-19 and being forced to make snap, history-defining decisions in a matter of days, and not what had become the long-normal process of months of consideration and consultation, has clearly emboldened the AFL to make this monumental rule change inside a week, and just a day before the first of 198 home-and-away matches.

But it comes at a cost, some of it literally. Depending on how individual players are contracted to their clubs (some have flat fees, some have match fees, most have match incentives), $3 million or thereabouts could be the collective cost for the game on teams fielding an extra player in 2021. At a time when each club's football department has been slashed by $3.5 million and budgets across the entire industry severely damaged.

In returning to 22 matches consisting of 20-minute (plus time-on) quarters and in locking in the Grand Final to a daytime Saturday timeslot, the AFL had recently given back to its fans some of the tradition which they had desperately sought.

In ordering the substitute rule, it has provided Clarkson and the coaches some of what they wanted.

Having been forced to take away so much from the game in the past 12 months, it is in a very giving mood on the eve of the 2021 season.