QBR was basically debunked this season as total garbage. Here is an example of just how bad or off it can be:
Week 3- 28-43, 281 yds, 65.1%, 2 TD, 1 INT, QBR-60.3, QB Rating-89.4
Week 15- 26-37, 231 yds, 70.3%, 2 TD, 1 INT, QBR-18.3, QB Rating-93.4
So in Week 3, Cutler had a few more incompletions, but a few more yards, with his QB Rating slightly lower, since QB Rating weights completion pct more important than yards. Either way the games were comparable and the QB Ratings were within 4 of each other. However, Week 3 is literally 3x better in QBR from Week 15 just because of 50 more passing yards but with a lower comp %? That is absolutely ridiculous.
Now look at Week 1:
18-36, 225 yds, 50.0%, 1 TD, 1 INT, QBR-29.6, QB Rating-67.5
So compare this with Week 15 and come up with a logical reason to how Cutler can have more completions, yards, comp%, and TD's yet a lower QBR in Week 15.
DVOA is way better, more accurate, and has been more consistent for a longer period of time:
DVOA:
1. Palmer
2. Dalton
3. Wilson
4. Big Ben
5. Brady
6. Cousins
7. Brees
8. Taylor
9. Cutler
10. Stafford
12. Newton
17. Rodgers
This was Cutler's best season as a Bear (highest DVOA was #13), and 2nd highest overall. He was 7th in his last year with Denver.