I think the biggest thing we saw was the lack of creativeness from Matt Nagy and his staff. His play-calling was so predictable. It was literally like clockwork. Here is a stat that represents how bad it was:
On all 32 NFL teams, the bears ranked 29th in passing rate on 2nd down and 8+ yards to go. I can understand if you have one of the best running game in football. However, when you have a lackluster offensive line, you can't afford to run that often on second and long. Because that tends to bring in a 3rd and long and you ask that same offensive line to block for a long time. That is a recipe for disaster. One of the most effective ways to pivot out of that run game is by throwing quick passes and screens. That is basically an extension of the run game but you are able to give the ball to even more explosive players.
Hopefully, with the changes in the coaching staff, this will be a thing of the past and we will see some innovative play-calling and success will follow!