ESPN's new QB rating system

My sister Karen shared the Freakonomics post about the ESPN's new quarterback rating system. It was a great post and I'm so happy that she brought it to my attention. I didn't realize that the NFL's official Quarterback Passer Rating System was created in the 70s. I think it's time for a change and I think ESPN is on the right track.

1. I like that the new QBR attempts to take a more comprehensive view of the QB. The 4 basic components of the passer rating system seem to exclude the rushing game, sacks and fumbles.
2. Sometimes I just don't know if a passer rating is good or bad because the numbers don't start at 0. It seems like it will be easier to figure the QBR.
3. Last, but not least, I'm tickled that Jay Cutler looks "less effective" under the new system.

What do you think of the new system? Is it an improvement? Should it also look at defense as part of the rating system?