The problem Crosby faces is not getting another concussion. It is sustaining sub-concussive impacts. He will suffer many sub-concussive impacts in each game once he returns to the ice. His ability to skate at 100% intensity or effort has little to do with his ability to return to the game.

As Collins has stated directly, his Buffalo protocol only prepare the athlete to return to the game "physical symptom free." The iMPACT test only tests at a surface level. Even a full Neuro-Psych Assessment battery falls short of giving adequate information.

I doubt Crosby has any medical doctors overseeing his condition "who have a reasonable understanding of how to test him for return to play condition." There are no standard tests for use by any professional that fully test for recovery condition.

I suggest that Crosby has been released to return to play based on a few criteria.
1. He is no longer experiencing head aches, even during or after physical exertion.
2. He has regained his vestibular functions to an acceptable level.
3. He has regained his reaction times to an acceptable level.
4. He has regained an acceptable level of his baseline cognitive skills.

What he has likely not been tested for are:
1. His reaction times when he is at the end of his on-ice shift.
2. His judgment skills when he is at the end of his on-ice shift.
3. His cognitive skills when he is at the end of his on-ice shift.
4. The above when he is oxygen deprived due the cumulative effect of exertion from a period of play.
5. The above (1-3) when his blood/body is flush with the waste from muscle efforts and the related pounding of play.

So, I would hope that he can keep track of how he feels and how he is thinking and is willing to pull himself from the game if he notices any deterioration of 1-3 skills above. Unfortunately, a deterioration of judgment skills often prevents making sound judgments to end play.

The days and weeks after returning to aggressive play will tell.