Depending upon whom you ask, the league has decided to hold the new pass interference rule hostage. Basically only the most egregious plays will be overturned, the likes of which were highlighted last season in the NFC Championship Game, which was the impetus for the rule.
There have been many instances this season already of challenges being issues to pick up or put down a flag on plays where there more or less clearly was an infraction, yet Al Riveron, made the decision to take no action, under the guise of it not rising to the requisite level of severity to make that sort of intrusion into the game.