Can't a concussion result even without a blow to the head? Like a sudden stop in a car or a heavy hit to the body that forces the brain to move around in its brain compartment?
Bad math. You're forgetting to subtract whoever it is that he'll be replacing, for one thing. And there are a few others.
I still do not advocate for trading for a guy that's not going to fit w/I the cap.
He's 36! McCabe comes through the next several years at only $4M. If they're going to give up a 4th or 5th for Johnson, fine, but McCabe is the better player and the better move. EDIT: Please remember that it needn't be a one-off for this season. The team lacks depth on D and we all know it.
At a certain point, he may even have been the Sabres' best defenseman. I've always loved his "special brand of mean," a phrase I used more than once here to describe his play. Get him.