You don't have to go too far to see why the Bears lost this game. In fact, you can look at Mike Glennon's very first snap to witness the beginning of the end.
The Bears line up in a simple run formation with WR Bellamy and TE Miller on the top of the screen, along with WR Wright on the bottom of the screen. TE Dion Sims is lined up next to Massie as the 6th lineman in protection.
As the ball is snapped, Glennon fakes the handoff to Jordan Howard, signaling a play action pass. Bellamy runs straight upfield along the left hash marks while Wright is running up the field along the right hash marks. The TE Miller is running to the flat on the left of the screen, while TE Dion Sims is taking on trying to block Clay Mathews off the edge. There is really not much for Glennon to diagnose here. He either throws deep down the middle of the field for Bellamy/Wright or to Miller in the flat. It looks as though his first read is to look downfield for the big play, hoping someone bit on the play action.
Unfortunately, both Bellamy and Wright are covered with the safety over the top of them. So Glennon goes to his other read, his outlet TE Miller. Miller is open with a relatively huge cushion and there is absolutely no pressure around Glennon to disrupt him.
Even though there is no pressure in Glennon's face, he becomes indecisive. For some reason he does not pull the trigger to his TE Miller and instead looks upfield again to Bellamy/Wright. This was a critical error by Glennon, as they are still covered and the rush is getting closer. On top of that, Glennon is standing in the exact same spot as he was at the very beginning of his drop back, making him a sitting duck for the pass rush.
Now in a state of panic, Glennon turns back to his TE Miller. At this point, Glennon has done more than enough damage and should just take the sack. But he foolishly tries to get the pass off to Miller. Honestly, if Clay doesn't hit Glennon and he gets that throw off in this situation, it's probably a pick 6. But he's drilled at the very beginning of his throw motion...game over.
Pre snap God Mike Glennon should have identified the Sims/Mathews matchup before the ball was snapped and known that he didn't have 17 seconds to survey the field. Even still, he only had basically two reads to look through, and the line gave him more than enough time on this play. Also, Glennon hangs Sims out to dry by standing in the same exact spot for the entirety of the play, giving Mathews an easy target.