I would imagine so...these things don't simply get dropped on you without any prior knowledge.
Anyway, the point here, IMO, is simple: it's a banned substance, so a player has to be responsible for not putting it into his body.
The coaching staff does have some skin in the game here, as they need to make clear what is and isn't acceptable--for folks that aren't in the locker room every day (which is all of us), it certainly appears that Rex is lax in that area.
As to the on-field effect, well, we'll have to see. Bryant is a decent back-up, but where this really hurts is in the rotation. We'll have to hope that Worthy and a guy like Casey Walker or Alameda Ta'amu can take 20 snaps at NT per game to keep the horses up front fresh, and that Rex truly can manufacture pressure when the guys on the field know his scheme and are communicating well.