Whether a player is fined for a personal foul has become the new way of deciding that a player probably didn't deserve the flag. Such is the case with Green Bay Packers LB Clay Matthews. From Pro Football Talk:
The league office confirmed to PFT that Matthews did not get fined this week.
Occasionally the NFL admits when an obvious mistake is made. The NFL issued a statement after the 49ers beat the Lions in which they said that the ball was incorrectly spotted after a punt return.
Now we can tell when a mistake was made even if the NFL doesn't issue a statement. If there is no fine that week, then the NFL probably did not agree with the call. It could cost your team the game, but at least it won't cost your $15,000!
The same thing happened to Desmond Bishop earlier this season when he wasn't fined for a hit on Cam Newton that drew a personal foul. Mike McCarthy was pretty outspoken about that one, but maybe he was just as outspoken for his player behind the scenes this week.
I still don't know what the answer is here because quarterbacks are still suffering concussions, and defensive players and their coaches are frustrated with these close penalty calls.