IMO, it is in no way a back of box feature they should use to sell the game.
It's 95%
PR related and 5% gameplay related. It's simply another game injury - the only difference is that your players will be out longer than just a couple plays now if they get a concussion.
That's pretty much it. No option to put them back in with a re-injury rating risk. If they get concussed, they are out for the game - period. Show a cut--scene of them going off in a cart with little stars and birdies floating around their head or something. But leave it at that.
Concussions are big deals, I agree. Keeping a player out of a game - or out several games pending post-concussion results, is a good thing.
Should they sell it on the box? Absolutely not.
This is simply a tip of the hat to the NFL Rules Committee and the general NFL player safety consciousness.
To glorify this as a new "feature" would be borderline insulting. Just put it in the game and let it play out on it's own. Blog about it if you want. But don't sell it.
Just my 2 cents.