The Bears have been a major disappointment this season. But the Lions are in worse shape. Detroit has dropped four in a row. 
The teams just met three weeks ago and Chicago won, 20-13. The Lions didn't have Matthew Stafford in that game and they won't have him Thursday. The Lions also might not have second-stringer Jeff Driskel either.
Driskel hurt his hamstring in the Lions' loss to the Redskins this past Sunday. If Driskel can't go, the Lions would be forced to turn to rookie David Blough. He's never taken an NFL snap. Even if Driskel can play his mobility would be limited. Driskel's strength is his mobility. 
Chicago's defense ranks fourth in fewest points allowed and in fewest yards allowed. The Lions' defense, by contrast, ranks 29th in total yards and 26th in scoring defense. The Bears surrender 81 fewer yards per game than the Lions and nine fewer points a game. 
The Bears' biggest problem is Mitchell Trubisky. He plays well, though, against the Lions. Trubisky completed 16 of 23 passes for 173 yards and three touchdowns in the earlier victory against the Lions. Trubisky faced the Lions once last season and passed for 355 yards and three touchdowns in a 34-22 win.