The offense had 27 points going in to Q4, they should be able to coast on a lead like that. I think they probably should have gone to a gameplan that chewed up more clock with lots of short & intermediate routes and runs with Michael, but they're not the reason the game ended up being close. The Bears targeted Randall hard because they knew he couldn't handle the soft zone coverage they were playing. That's a DC issue IMO, don't put Randall in a position to fail. Cover 3 Man is the late game D that this defense is built for.
I also think the front 7 is not getting enough criticism for the collapse. The Bears OL was getting downfield and covering up the 2nd and 3rd levels. Howard had open lanes to run in and Barkley had plenty of time. Inexcusable that they couldn't even pressure Barkley.