The AFL Commission is expected to hand down its decision early this week.
In my view it is a change that must take place, albeit with a careful consideration of the detail as to how it would work in practice.
Go through a practical example of what might happen in 2013 when a player receives a knock to the head and you begin to understand why the decision is, to use an unfortunate phrase, a no-brainer.
The player would be taken from the ground for assessment for as long as 20 minutes.
Logic suggests some time will need to elapse before the testing starts and it could then take between five to 10 minutes to fully assess the player.
While nearly 20 minutes might seem like a long time for a team to be down to two rotations - particularly if two concussion assessments per game take place - significant time is needed to make the best diagnosis.
'Significant time' was the recommendation of the Consensus Statement on Concussion in Sport released in the British Journal of Sports Medicine last Tuesday and it's likely to be one repeated in conservative concussion guidelines due for release next week.
Without a structure to support such advice, however, it will be under more pressure than it needs to be.
Inside the world of AFL sport science
It's likely a doctor will also examine video footage to see whether a player suffered a loss of consciousness, an impact seizure or got the staggers or none of the above after receiving a knock.
This will make those making the diagnosis fully aware of what preceded the assessment.
Suddenly, if that scenario of two concussion assessments per game unfolds, teams might be down to two rotations for a third of the game if a concussion sub is not allowed.
Imagine the impact such extra workload would have on the players still playing.
To say young players will be cooked is not putting too fine a point on it.
It's not difficult to imagine the gap on the scoreboard widening at breakneck speed between, for example, Gold Coast and Collingwood if the Magpies were suddenly one rotation up for 15 minutes or so. That's not what anyone wants.
At least with a fresh player introduced while the assessment happens the Suns would be a fighting chance.
Alternatively, the game might crawl to a walk. Without a concussion sub teams would be instructed to chip it around while their rotations are down in order to chew up time. That is not a good spectacle.
Of course there is always the chance that an early injury would see teams without a sub to replace a player undergoing a concussion assessment, but the Commission should not let the perfect solution be the enemy of the good solution.
Re-think on concussion sub after journal
While the concussion guidelines are likely to make the doctors' jobs even tougher, everyone accepts any impost if it's for the players' benefit. However doctors will have even more headaches if a coach is wondering in their ear whether a player is likely to be subbed out of the game or not.
That, as Mick Malthouse conceded a couple of weeks ago, is what will happen if no concussion sub is introduced.
"We can say all we like pre-match [but] during the match we're going 'oh we're getting tossed about in the middle here because we haven't got the resources to replenish'," Malthouse said.
Believe me, illogical emotions can take hold pretty quickly in the heat of battle.
Evidence suggests the sub has already eased pressure on diagnostic decisions in any event. The concussion sub will be necessary to achieve that objective too once conservative concussion guidelines are introduced.
Some have wondered whether the system could be flouted for tactical advantage. While that might be a reasonable concern if an injury sub was being considered, it's next to impossible to imagine a club deliberately imposing a concussion assessment to get a player replaced.
The game should be viligant of course, but it also needs to give teams enough respect to expect that they won't flout the rule.
Given that, the AFL Commission should consider the possibility that a fit sub should be able to be used at any time, even if the available sub had been subbed out of the game for tactical purposes earlier.
The negatives are that players may be on and off the ground for extended periods of time.
That is a tough conditioning challenge but one clubs are equipped to handle.
While it surely won't happen this year, two subs on the bench for such purposes should not be out of the question either.
Perhaps that is a bridge too far at this stage, perhaps not.
The detail of how it will work in practice warrants careful consideration but the concussion issue is too important to wait.
Tuesday's consensus statement on concussion in sport – released via the British Journal of Sports Medicine – made the view of the experts clear: sports should consider rule changes to ensure the assessment of players suspected of suffering head knocks can occur "without affecting the flow of the game or unduly penalising the injured player’s team".
The concussion sub must be introduced to support the intent of concussion guidelines.
