The concussion substitute fixed one problem and opened a second

An extra permanent change removes the incentive to rush an assessment, and hands teams a spare substitution that is hard to police.

Before the additional change existed, a coach assessing a head injury was doing arithmetic. Three substitutions, one already used, forty minutes left. That arithmetic ended careers, and the rule that removed it was overdue and correct.

Now look at where the incentive moved. The permanent concussion substitute is, from a purely tactical standpoint, a free change, and in several codes the opposition receives one too, which was added precisely because officials could see what was coming. A team that has exhausted its normal allocation and needs a tiring midfielder off has a route available, and the gatekeeper for that route is a doctor employed by the club.

I do not think this is being abused often. I think it is being abused occasionally, and occasionally is enough to corrode the rule, because the whole structure depends on referees accepting the doctor's word without argument. That deference is the point. You cannot have officials second-guessing a head injury assessment on the touchline. So the law is deliberately unfalsifiable in the moment, which means the only possible enforcement is retrospective, and retrospective enforcement requires someone to review the assessment paperwork afterwards and be willing to sanction a club doctor.

Very few competitions do that with any seriousness. The ones that do have found what you would expect: a small number of cases where the recorded symptoms are thin and the substituted player is available and unremarkable four days later.

There is a second consequence that gets less attention. Because the additional change is permanent, an athlete removed under the protocol cannot return even if the assessment clears them, which is exactly right for safety and creates a subtle pressure not to start the assessment at all in a tight game with a key player. The rule solved the coach's dilemma and rebuilt a smaller version of it one step earlier in the sequence.

Fix the audit, not the law. Every protocol activation should generate a filed assessment reviewed by an independent officer, with the sanction landing on the club rather than the practitioner, because a doctor who feels their registration is at stake will make worse decisions, not better ones. The rule is right. The trust it requires has to be verified somewhere, and right now it mostly is not.