I don't think it's an overreaction at all. He was really bad in that first half. I'm sure someone will do an all 22 analysis that will help explain why he was bad and justifiably shift some of the blame, but much of the decision making and accuracy issues were on him.
Yes, the receiver group could have helped him out more, and a better group would have. But calling out Hollins because he had to do a 180 going full speed on a crossing route or get completely turned around and have to change direction on a go route in a dome to locate poorly thrown balls isn't it. Josh also had Kincaid for a would be TD but instead gift wrapped a badly underthrown INT that was luckily dropped.
Bills have above average OL, TE, and RB groups. They have a top QB. Their WR group is poor, and without Shakir it's really poor. Again, we had to do a lot of cap gymnastics just to get to this point. You can't have everything, and some weeks it's going to bite you. Not this week - this week was on Josh.