Stafford has a knee problem that has been affecting his throwing motion all season. Its probably why he's constantly throwing off his back foot like he's Vince Young or Jamarcus Russell or something. It also doesn't help that his #2, #3, and #4 WRs are out, and his starting TE. Plus all of them have a bad case of the drops this season. Also keep in mind that as god awful as the Cardinals are, they still have an elite pass defense.
As for Cutler, he's both an idiot, and he only has 1 legit WR. I'm more inclined to blame poor coaching for these teams problems than QBs. After all, Stafford's about to throw for 5000 yards again.
A lot of Stafford's problems on the field come from the Lions running a very vanilla offense and over-reliance on Megatron. If the Lions were to be more creative in their playcalling, Stafford would look a lot better on the field. Add to that, a couple of HORRIBLE calls from Jim Schwartz costing them games this year, and it's pretty clear that most of Detroits problems are self-inflicted.
Cutler has a less talented receiving corps around him, making his job harder even with better play calling (in general).