I doubled-checked this. It was not a new rule, but a re-emphasis of the 1978 rule. The league admitted they missed 6 PI against NE in the Pats-Colts playoff game.
http://web.archive.org/web/20040215093250/http://msnbc.msn.com/id/4079437/
As for roughing the passer, I would like to see a link for your stats. From what I’ve seen, Brady seems to get favorable calls in big games.
Correct. The PI wasnt a rule change, it was an interpretation change. The words in the rulebook didnt change, but the way it was called changed dramatically.