It's not just fans on twitter, take a look around, plenty of sportswriters out there questioning him too. He is 3-6 in the playoffs, hasn't gotten us to the Super Bowl, call it an overreaction to last night if you want but many of us haven't been happy with him for a while now. It's not that hard to win in the regular season if you have a good QB and he does seem to be a good OC. But he is a terrible at game management and it has been 7 years. He could probably use a fresh start somewhere else too.
And I said he has lost the fanbase, never said anything about everyone dropping their season tickets over it.