I think we're underestimating the seriousness of Manning's problem. There could be several reasons this hasn't been addressed by Sark. The simplist would be that the experts who've examined Manning says that in his case, the one (or more) he's had are not a problem and he's okay to play. Fingers crossed.
 
	That said, I don't think we'll see him this weekend and quite possibly the next game. They'll do everything they can to protect Arch...
 
	This from Google AI. 
 
	Increased risk with each concussion 
	A prior concussion makes you significantly more susceptible to another one. Research on athletes shows that having a history of concussion dramatically increases the risk of suffering another, and the risk escalates with each subsequent injury. 
	
		Weakened brain tissue: A concussion is a type of traumatic brain injury that happens when the brain moves or twists inside the skull, which can weaken the surrounding tissue.
	
	
		Vulnerability window: The chemical changes that occur in the brain after an injury can leave it debilitated for an extended period, sometimes up to a year. A second impact during this time can be more damaging.
	
	What's the word on Caldwell's backup?