[Fart]

Idk about the crown hit thing but I never liked the tuck rule at all.

Basically the runner with the ball can't initiate contact on a defender head first, outside of the tacklebox. i.e. when Trent Richardson hit that dude head first and popped his helmet off. If the runner turns his shoulder, or does anything to protect themselves from the hit no penalty will occur. If it's helmet to helmet, no penalty. If it's out of bounds contact, no penalty. They have to pretty much hit THEM with the crown of their helmet first for it to be a penalty (15 yards)
I don't know how it will playout until the season starts, its still not 100% clear on how it will be called in games.. I don't remember a lot of backs last season trying hit hit dudes head first lol. All teams voted on the rule and it passed 31-1, the Bengals being the only team to oppose it.

As for the tuck rule, I always thought it was kind of dumb. When it happens in a game and its not a fumble, it almost always gets played out as if it were. So to me thats just less wasted time between snaps and shit.. it passed 29-1-2, the Steelers voting against it, and the Pats and Skins did not vote.