Rodgers' last 100+ QB-rating performance came against the Chargers in October of 2015. Since then his QB rating has averaged 82 and the Pack have gone 5-7.
There could be any number of reasons why his performance has dropped, but the bottom line is when you put Aaron Rodgers against a good defense - he's just slightly better than average. He can get streaky, he can win games, he can make big throws. But for whatever reason - he just doesn't do it very often against the better teams.
I'm an Aaron Rodgers fan, but those stats just don't lie.