Have to agree with that. FIFA will be under pressure to re-look at their concussion protocols as there were at least 4 instances where I thought they guy should not have come back onto the field. First, the player needs to be independently evaluated, i.e. not by his/her own medical staff. The magic spray does not work on the head. Second, and I know it’s a major break in tradition; but, the injured player’s team should be able to put in a ‘temporary’ sub to provide medical officials with eth 6 or so minutes to properly evaluate a head injury. After the evaluation is done, the temporary sub comes off without burning one of the team’s 3 subs if the injured player is deemed fit. If the injured player is not, then the temporary sub becomes a permanent sub and one of the substitutions is used. A player’s long-term health is much more important than tradition.
It takes longer than 360 seconds to evaluate and determine a potential concussion. In American football, the protocol calls for the player's helmet to be taken away immediately and as soon as the player is escorted to the locker room (not the bench), he must take off his cleats. IF the player comes back, it typically isn't for about the time it takes to play a quarter, which is about 35-45 minutes.
I can certainly get behind your concussion-sub idea, but there will absolutely be managers who try and circumvent the spirit of the rule. So in order to prevent this, I would add:
1) If the concussed player is able to return and is re-subbed into the game, the concussion-sub is done for the day.
2) The concussion sub cannot be subsequently replaced by the 3 otherwise allowable subs (even for an injury). I.e. ONLY the originally concussed player can replace the concussion sub.
3) If the originally concussed player must come out again after reentry, the side must play with 10 for the remainder of the match or use an otherwise allowable sub.
4) No concussion sub will be allowed if the 3 otherwise allowable subs have already been exhausted (Guards against faking a head injury late in the game to allow a fresh player on). The side plays with 10.