I don't know if concussions are different than any other injury. However, generally as a rule, I bench a guy with one. The same goes for the pesky neck injuries too. (Esp. with Off or Def lineman). Overall, I try and limit any injured player seeing playing time. But in saying that, I try and develop teams that have some kinda depth over time because injuries can,do,and will happen. Usually right before a crucial matchup,division game,or playoffs. (Is that defined as bad karma or bad juju?)